Jammed keysafe. Grrr.....

[mike]

Social Services lent me a temporary keysafe for an elderly relative on Friday, until I could get over and instal a permanent one. It's this one:

http://www.keysafe.co.uk/portable_ge_keysafe_001025_8264

It seemed dodgy as they were trying to set the code but I assumed it was just stiff as it was new.

By Saturday it was playing up, and now some of the numerical buttons won't push in and the keys are stuck inside it.

Their solution so far has been to bang on the windows and wave until my deaf, increasingly confused, 97-year old relative spots them and lets them in (or not).

This doesn't seem like a viable long-term solution to me but apparently the wretched thing is on loan to Social Services from another department and they're reluctant to do anything that might damage it in case they're not lent any more.

I don't expect anyone to tell me how to break into the bugger on a public newsgroup but does anyone have any ideas I might try to get the swine working again. I know the code.

At the moment the situation reminds me of the old Two Ronnies joke about someone with a temperature to whom the police sent round a social worker with a megaphone to try and talk it down.

[Ericp]

On Tue, 25 Jun 2013 11:21:21 -0700 (PDT), mike <mike...@yahoo.com>
wrote:

Try a decent penetrating oil or WD40 as a last resort.

[newshound]

My usual approach to things like stuck buttons is to spray every
entrance liberally with penetrating lubricant, then jiggle anything
which can or should move. Personally I consider WD40 to be OK for this,
but some don't like it because once the "thin" oil has evaporated it
leaves a thicker sticky oil which may attract debris. The "thin oil
only" products are often called dewatering fluids.

It's definitely best to use an aerosol because they "foam up" as the
propellant escapes, and as long as you can get it into the works, the
foaming may help to dislodge debris.

Not applicable in your case I guess, but ultrasonic cleaners can be
effective, I'd probably use white spirit since it is a hydrocarbon and
thus wets metal effectively, and has some lubricating properties.

[polygonum]

On 25/06/2013 19:53, newshound wrote:
> My usual approach to things like stuck buttons is to spray every
> entrance liberally with penetrating lubricant, then jiggle anything
> which can or should move.

Are you getting confused with Steve Firth's naked man thread?

:-)

--
Rod

[Bod]

On 25/06/2013 19:53, newshound wrote:

Plus gas?

[newshound]

Yes, plus gas used to be very good (and probably still is). I meant that
I use white spirit in my cheap US cleaner which I think came from Maplins.

[bod]

Righto.

[Tim+]

mike <mike...@yahoo.com> wrote:
> Social Services lent me a temporary keysafe for an elderly relative on
> Friday, until I could get over and instal a permanent one. It's this one:
>
> http://www.keysafe.co.uk/portable_ge_keysafe_001025_8264
>
> It seemed dodgy as they were trying to set the code but I assumed it was
> just stiff as it was new.
>
> By Saturday it was playing up, and now some of the numerical buttons
> won't push in and the keys are stuck inside it.
>
> Their solution so far has been to bang on the windows and wave until my
> deaf, increasingly confused, 97-year old relative spots them and lets them in (or not).
>
> This doesn't seem like a viable long-term solution to me but apparently
> the wretched thing is on loan to Social Services from another department
> and they're reluctant to do anything that might damage it in case they're
> not lent any more.
>

Personally, I would have thought that if it's dodgy it shouldn't be reused
and you'd be doing everyone a favour by attacking it with an angle grinder
or big hammer.

Tim

[Peter Parry]

On Tue, 25 Jun 2013 11:21:21 -0700 (PDT), mike <mike...@yahoo.com>
wrote:

>I don't expect anyone to tell me how to break into the bugger on a public newsgroup but does anyone have any ideas I might try to get the swine working again. I know the code.

Try using the code but in a different order, so 4321 or 3214 etc
rather than 1234. Many mechanical locks of that sort will accept the
numbers in any sequence.

[Brian Gaff]

Just before the angle grinder.
Brian

--
From the Sofa of Brian Gaff Reply address is active
"Ericp" <er...@blueyonder.co.uk> wrote in message
news:sapjs8tq92392j933...@4ax.com...

[DerbyBorn]

"Brian Gaff" <Bri...@blueyonder.co.uk> wrote in news:kqe4l5$pfc$1@dont-
email.me:

> Just before the angle grinder.
> Brian
>

I realise it is not a wall mounted one - but the wall mounted ones are
utter shite. If you tighten them to the wall and get a bit of distortion
due to the wall not being flat then they jam. Also the space for keys is
absolutely pathetic.

[mike]

On Tuesday, June 25, 2013 10:21:46 PM UTC+1, Peter Parry wrote:

> Try using the code but in a different order, so 4321 or 3214 etc
>
> rather than 1234. Many mechanical locks of that sort will accept the
>
> numbers in any sequence.

Thanks for all the replies.

Social Service have just phoned to say that one of the carers managed to get it open last night... so they have put the keys back in on the basis that it's probably just a bit stiff. Oh, jeez...

I will give the WD40 or some silicone oil a go. Don't have any Plusgas.

I tried the numbers in other sequences as I realised that would also work (in theory) but one number just wouldn't depress.

Out of interest, could someone just confirm (or correct) my hazy recollection of O-Level probability:

With a 4-digit dial-type key safe, there is a total of 10x10x10x10 = 10000 possible combinations of which only one will work. So probability of entering working code by chance is 1 in 10000.

But with a push-button safe where no number can repeated in the 4-digit sequence, the total number of possible combinations is 10x9x8x7 = 5040, and (because the digits can be entered in any sequence) the total number of working codes is 4x3x2x1 = 24, so 24 codes in a total of 5040 or probability of entering working code by chance is 1 in 210.

[F]

On 26/06/2013 11:09 mike wrote:

> Out of interest, could someone just confirm (or correct) my hazy
> recollection of O-Level probability:
>
> With a 4-digit dial-type key safe, there is a total of 10x10x10x10 =
> 10000 possible combinations of which only one will work.

It's simpler than that: any whole number between 0000 and 9999. So, yes,
10000.

--
F

[Gazz]

> Out of interest, could someone just confirm (or correct) my hazy
> recollection of O-Level probability:
>
> With a 4-digit dial-type key safe, there is a total of 10x10x10x10 = 10000
> possible combinations of which only one will work. So probability of
> entering working code by chance is 1 in 10000.
>
> But with a push-button safe where no number can repeated in the 4-digit
> sequence, the total number of possible combinations is 10x9x8x7 = 5040,
> and (because the digits can be entered in any sequence) the total number
> of working codes is 4x3x2x1 = 24, so 24 codes in a total of 5040 or
> probability of entering working code by chance is 1 in 210.

Usually even less chance of getting the number wrong, as you can usually
tell the buttons pressed for the code by them being clean whilst the rest
are filthy, or wear on the commonly used buttons etc,

tho in this particular case, the code is changed regularly it seems, wonder
if one of the code change levers/turn screws isnt properly engaged, causing
the stiffness of one button in the code.

[Dave Liquorice]

On Wed, 26 Jun 2013 11:15:35 +0100, F wrote:

>> With a 4-digit dial-type key safe, there is a total of 10x10x10x10
=
>> 10000 possible combinations of which only one will work.
>
> It's simpler than that: any whole number between 0000 and 9999. So, yes,
> 10000.

*Maximum* of 10000 but you are forgetting that you can only use each
digit once and that the digits can be entered in any order so 1234 is
the same as 2134 or 2314 or 2341, etc, etc...

I'm not sure that the odds of entering the working code are 1 : 210
from the other post. I'm not a statastion or probabilty expert but
have a sneaky feeling there is even more to it than meets the eye.

--
Cheers
Dave.

[charles]

In article <32cd7342-12f3-4988...@googlegroups.com>, mike

I bought some for our village hall. It jammed almost immediately. The
solution (to get it open) was to hit it hard on top with a hammer.

--
From KT24

Using a RISC OS computer running v5.18

[John Williamson]

Add to that the fact that with age, the buttons wear, so you just need
to push the four worn ones in any order.....

--
Tciao for Now!

John.

[dennis@home]

You missed where he said dial type, they are not the same as the push
button ones.

[dennis@home]

On 26/06/2013 17:42, charles wrote:

> I bought some for our village hall. It jammed almost immediately. The
> solution (to get it open) was to hit it hard on top with a hammer.
>

This type appears to be better

http://www.thesafeshop.co.uk/products/ge-c500-police-approved-keysafe.html?ACODE=googlebase&gclid=CLPyk5bAgrgCFZLKtAod10IA8Q

It has 4 times the number of combinations and is easier to operate.
You don't need to enter the code again in order to lock it.

You can buy them cheaper.

[Dave Liquorice]

On Wed, 26 Jun 2013 20:52:53 +0100, dennis@home wrote:

>>>> With a 4-digit dial-type key safe, there is a total of
10x10x10x10
>>>> = 10000 possible combinations of which only one will work.
>>>
>>> It's simpler than that: any whole number between 0000 and 9999.
So,
>>> yes, 10000.
>>
>> *Maximum* of 10000 but you are forgetting that you can only use
each
>> digit once and that the digits can be entered in any order so 1234
is
>> the same as 2134 or 2314 or 2341, etc, etc...
>

> You missed where he said dial type, they are not the same as the push
> button ones.

But we aren't talking about dial type but push button. The dial type
was only mentioned to get the maximum number of permutations from 4
digits. The rest of the probabilty post is about push button like the
push button key safe mentioned at the start of the thread.

--
Cheers
Dave.

[dennis@home]

The post you replied to, as in the quote you have included, states "with
a 4 digit dial type" you get 10000 codes and you can use each digit more
than once on them.

[The Medway Handyman]

Keysafe say 1024.

>
>
>
>


--
Dave - The Medway Handyman www.medwayhandyman.co.uk

[The Medway Handyman]

And that most elderly people use their year of birth as the code.

[Dave Liquorice]

On Wed, 26 Jun 2013 22:46:47 +0100, dennis@home wrote:

> The post you replied to, as in the quote you have included, states "with
> a 4 digit dial type" you get 10000 codes and you can use each digit more
> than once on them.

English comprehension is not a strong point is it?

What is so hard about:

"The dial type was only mentioned to get the maximum number of
permutations from 4 digits."

and:

"The rest of the probabilty post is about push button like the push
button key safe mentioned at the start of the thread."

--
Cheers
Dave.

[mike]

Ah, yes:

http://www.keysafe.co.uk/frequently_asked_questions

I assume this is how they've arrived at that figure:

If there are ten buttons and each can be in one of two states ("on" or "off"), then 2 raised to the power 10 would give 1024 (and that would explain why the new 12-button safe has 4096 combos: 2 raised to the power 12). But it fails to point out that multiple combinations will open the safe.

And I don't see why their methodology is right and mine is wrong.

But if they are right and there are only 1024 possible combos --- and there are 24 codes that will work --- the probability of guessing one of the codes is even higher.

[John Williamson]

Damn! I thought that would be a nice secure number to use.... (Only joking.)

[dennis@home]

On 27/06/2013 09:59, Dave Liquorice wrote:
> On Wed, 26 Jun 2013 22:46:47 +0100, dennis@home wrote:
>
>> The post you replied to, as in the quote you have included, states "with
>> a 4 digit dial type" you get 10000 codes and you can use each digit more
>> than once on them.
>
> English comprehension is not a strong point is it?

Do i really need to repeat whole posts you have made to prove you are
wrong and that my comprehension is correct?
It looks like it so here is the first one..

Quote on 26/06/2013 14:15, Dave Liquorice wrote:

On Wed, 26 Jun 2013 11:15:35 +0100, F wrote:

>> With a 4-digit dial-type key safe, there is a total of 10x10x10x10
=
>> 10000 possible combinations of which only one will work.
>
> It's simpler than that: any whole number between 0000 and 9999. So, yes,
> 10000.

*Maximum* of 10000 but you are forgetting that you can only use each
digit once and that the digits can be entered in any order so 1234 is
the same as 2134 or 2314 or 2341, etc, etc...

I'm not sure that the odds of entering the working code are 1 : 210
from the other post. I'm not a statastion or probabilty expert but
have a sneaky feeling there is even more to it than meets the eye.

......... End quote


Now where exactly does it say its anything other than a four digit dial
type and why do you think it can't use all the digits fro zero to nine
on any dial and that the order doesn't matter?

If anyone can't comprehend its you.
Stop wriggling.

End of it!

[The Medway Handyman]

As I may have mentioned before, my daughter is a paramedic in London.
Whenever they get a "grey lady down" call, if they haven't been given
the code, they ask a neighbour how old the person is & try the year of
birth. Apparently in works in 8 out of 10 cases :-)

[The Medway Handyman]

On 27/06/2013 11:03, mike wrote:
> On Thursday, June 27, 2013 8:25:30 AM UTC+1, The Medway Handyman
> wrote:
>> On 26/06/2013 11:09, mike wrote:
>
>>> But with a push-button safe where no number can repeated in the
>>
>>> 4-digit sequence, the total number of possible combinations is
>>
>>> 10x9x8x7 = 5040, and (because the digits can be entered in any
>>
>>> sequence) the total number of working codes is 4x3x2x1 = 24, so
>>> 24
>>
>>> codes in a total of 5040 or probability of entering working code
>>> by
>>
>>> chance is 1 in 210.
>>
>
>> Keysafe say 1024.
>
> Ah, yes:
>
> http://www.keysafe.co.uk/frequently_asked_questions
>
> I assume this is how they've arrived at that figure:
>
> If there are ten buttons and each can be in one of two states ("on"
> or "off"), then 2 raised to the power 10 would give 1024 (and that
> would explain why the new 12-button safe has 4096 combos: 2 raised to
> the power 12). But it fails to point out that multiple combinations
> will open the safe.

That's cheating!

>
> And I don't see why their methodology is right and mine is wrong.
>
> But if they are right and there are only 1024 possible combos --- and
> there are 24 codes that will work --- the probability of guessing one
> of the codes is even higher.
>

As others have said, worn buttons are a dead give away. Also 1,3,7,9
which are the four corners and, on electronic ones 1,4,4,7 - 2,5,5,8
-and 3669 (straight down, with centre repeated).

[The Medway Handyman]

On 25/06/2013 19:21, mike wrote:
> Social Services lent me a temporary keysafe for an elderly relative on Friday, until I could get over and instal a permanent one. It's this one:
>
> http://www.keysafe.co.uk/portable_ge_keysafe_001025_8264
>
> It seemed dodgy as they were trying to set the code but I assumed it was just stiff as it was new.
>
> By Saturday it was playing up, and now some of the numerical buttons won't push in and the keys are stuck inside it.
>
> Their solution so far has been to bang on the windows and wave until my deaf, increasingly confused, 97-year old relative spots them and lets them in (or not).
>
> This doesn't seem like a viable long-term solution to me but apparently the wretched thing is on loan to Social Services from another department and they're reluctant to do anything that might damage it in case they're not lent any more.
>
> I don't expect anyone to tell me how to break into the bugger on a public newsgroup but does anyone have any ideas I might try to get the swine working again. I know the code.
>
> At the moment the situation reminds me of the old Two Ronnies joke about someone with a temperature to whom the police sent round a social worker with a megaphone to try and talk it down.
>

AAMOI, about 3 years ago I applied to be the approved installer for
Keysafe in the ME postcodes. I still am AFAIK.

Filled in numerous forms, sent copies of my PLI & CRB + a photo. Got a
certificate & identity badge back & waited for the jobs to roll in.

I'm still waiting. Not one single job in 3 years.

Mind you, at £48 a pop I'm not surprised.

[Vir Campestris]

On 27/06/2013 11:03, mike wrote:

> And I don't see why their methodology is right and mine is wrong.

Nor do I.

Let me work it backwards. There's a 4/10 chance of the first button you
press being one of the combination ones, then 3/9, then 2/8, then 1/7.

So your chance of getting it right is (4*3*2*1)/(10*9*7*8). That's 1 in 210.

Andy

[SteveW]

I've not yet reached that age (or that sex!), but no-one would have any
chance of guessing a link to my PIN of choice for alarms, access, etc. -
when I first needed one, I used the digits of an electronic component
that I was experimenting with at the time!

SteveW

[SteveW]

On 26/06/2013 11:09, mike wrote:

First button, 4 in 10 chance, second button 3 in 9 chance, etc.

1 / (4/10 x 3/9 x 2/8 x 1/7) = 210.

SteveW

[mike]

Having thought about this some more, I've concluded that the numbers on the push-button safe are a red herring as far as probability goes.

On the dial safe, you have four dials and each of those dials can be in any of ten positions (0-9). Additionally, the four dials must be in the one programmed sequence. Imagine laying out four suits of cards (minus the picture cards) and being able to choose any combination of one from each suite, left to right.

Now on the push-button safe, each button (or dial) only has two possible positions, on or off. It's like one suit of cards and the only combination choice you have is face up or face down. That's far fewer combinations. Because the numbers don't come into play, one face up card is the same as any other face up card.

So I think Keysafe's calculation of total permutations is correct, and mine is wrong because it assumes a sequence that isn't there.

Does that make sense?

With regard to possible opening combinations, I think both you and I have again assumed a sequence that isn't there. There's no 4x3x2x1 because there isn't a *sequence* of four numbers. There are ten buttons, each with a binary choice.

So the chances of you getting the first button right is 1 in 2, the chances of getting the second right is also 1 in 2 and so on. This works out as 1/(2 to the power 10) with is 1/1024 which means there is only one combination that will work --- and that is to get all four right (but the order that you push them in doesn't matter).

Again, think of a suit of cards, 6 face up, 4 face down. It doesn't matter which order you turn them in as long as you get the same four face up.

Plausible? Correct? Or a load of old cobblers?

[Bob Eager]

I used to use one that was the last four digits of a long defunct phone
number that meant a lot to me....

--
Use the BIG mirror service in the UK: http://www.mirrorservice.org
My posts (including this one) are my copyright and if @diy_forums on
Twitter wish to tweet them they can pay me £30 a post
*lightning surge protection* - a w_tom conductor

[Bob Eager]

I asked a tame mathematician today and she said it was 210 straight away.

[dennis@home]

I always set a five or six digit code to beat the ones that think they
only have four digit codes.
It works.

The one described is a cheap (less than £20) key safe (unless you pay
the £48 SSP some people charge), there are better ones about for about £45.

My local authority no longer fits the type in the photo and hasn't for a
few years.

[Dave Liquorice]

On Thu, 27 Jun 2013 15:14:58 -0700 (PDT), mike wrote:

> Now on the push-button safe, each button (or dial) only has two possible > positions, on or off. It's like one suit of cards and the only
> combination choice you have is face up or face down. That's far fewer
> combinations. Because the numbers don't come into play, one face up
> card is the same as any other face up card.

The "numbers" do come into play as once you have used a "number" from
one of your four stacks of cards you can't use it from any of the
remaining stack(s).

> So the chances of you getting the first button right is 1 in 2,

50:50 where does that come from? You have ten buttons and any four
buttons could be correct so isn't that 4 from 10? (1:2.5), next
choice is 3 from 9 (1:3), then 2 from 8 (1:4) and finally 1 from 7
(1:7)?

2.5 x 3 x 4 x 7 = 210

Curiously 2.5 x 2.5 x 2.5 x 2.5 = 39.0625 which is odd but possibly
not surprising as odds and probabilties are not particularly
intuative.

--
Cheers
Dave.

[Bob Eager]

On Fri, 28 Jun 2013 07:57:32 +0100, dennis@home wrote:

> On 27/06/2013 22:10, Vir Campestris wrote:
>> On 27/06/2013 11:03, mike wrote:
>>> And I don't see why their methodology is right and mine is wrong.
>>
>> Nor do I.
>>
>> Let me work it backwards. There's a 4/10 chance of the first button you
>> press being one of the combination ones, then 3/9, then 2/8, then 1/7.
>>
>> So your chance of getting it right is (4*3*2*1)/(10*9*7*8). That's 1 in
>> 210.
>>
>> Andy
>
> I always set a five or six digit code to beat the ones that think they
> only have four digit codes.

The optimum would appear to be a 5 digit code - the odds go to 1 in 252.
With a six digit code they go back to 1 in 210.

[The Medway Handyman]

There is a very old gambling scam called the Six Card Swindle.

Two picture cards and four spot cards are face down & mixed up. Both
players place Ł1 into the pot & the punter turns over any two cards.

You explain to him that even though its 2-1 in his favour, you will play
even money.

If one or both are picture cards, he loses & you take the pot.

If both are spot cards, he wins the pot.

Played as a 'freeze out' bet. You both start with Ł10 & play till one
of you runs out of money - it will be the punter.

I have earned loads of free beer on this :-)

[mike]

On Friday, June 28, 2013 8:26:29 AM UTC+1, Dave Liquorice wrote:
> On Thu, 27 Jun 2013 15:14:58 -0700 (PDT), mike wrote:

> > Now on the push-button safe, each button (or dial) only has two possible > positions, on or off. It's like one suit of cards and the only
>
> > combination choice you have is face up or face down. That's far fewer
>
> > combinations. Because the numbers don't come into play, one face up
>
> > card is the same as any other face up card.

> The "numbers" do come into play as once you have used a "number" from
>
> one of your four stacks of cards you can't use it from any of the
>
> remaining stack(s).

The 'numbers' don't come into play in the sense that each button (unlike a dial) can't represent 0 to 9; it can only represent on or off, 0 or 1, face up or face down. And you can repeat them because, if you have ten buttons that are either on or off and four have been set to "on", then "on" is repeated four times.

> > So the chances of you getting the first button right is 1 in 2,
>
>
>
> 50:50 where does that come from?

The button can have one of two states: selected or not selected, on or off. If you choose at random you'll have a one in two or 50:50 chance of getting the right one.

> You have ten buttons and any four
>
> buttons could be correct so isn't that 4 from 10? (1:2.5), next
>
> choice is 3 from 9 (1:3), then 2 from 8 (1:4) and finally 1 from 7
>
> (1:7)?

> 2.5 x 3 x 4 x 7 = 210

> Curiously 2.5 x 2.5 x 2.5 x 2.5 = 39.0625 which is odd but possibly
>
> not surprising as odds and probabilties are not particularly
>
> intuative.

I'm not saying I'm right and anyone else is wrong. I made the original posting and I'm questioning whether I'm right.

As Dave TMH has already pointed out, Keysafe gave a different number of total possible combinations to the one that I suggested. And I suggested why they might be right.

It's possible to make a particular explanation seem plausible but then you have to prove that the other plausible explanations that give different results are wrong.

I agree with you that probabilties are not particularly intuative. The Monty Hall problem was mentioned on here not so long ago and that's obviously quite contentious.

[David]

On Thursday, 27 June 2013 23:14:58 UTC+1, mike wrote:

> So the chances of you getting the first button right is 1 in 2, the chances of getting the second right is also 1 in 2 and so on. This works out as 1/(2 to the power 10) with is 1/1024 which means there is only one combination that will work --- and that is to get all four right (but the order that you push them in doesn't matter).

> .....

> Plausible? Correct? Or a load of old cobblers?

I think the problem with this analysis is that it would be correct if we didn't know the number of digits in the "combination". In other words, if it could be anywhere between zero and ten digits long.

But we know that there are only four buttons that should be "on". The above analysis doesn't take that into account.

[dochol...@gmail.com]

On Thursday, June 27, 2013 8:27:59 AM UTC+1, The Medway Handyman wrote:
<SNIP>

>
> And that most elderly people use their year of birth as the code.

Which of course simplifies your choice for the first two digits...
Looking at the maths it appears that when keysafe claim 1024 combinations they're using the entire range from no buttons pressed to all buttons pressed. If you include the three largest sets only (4, 5 and 6 buttons pressed) you'd get 772 combinations, but in fact it seems almost universal to use just 4.

[dennis@home]

On 28/06/2013 08:36, Bob Eager wrote:
> On Fri, 28 Jun 2013 07:57:32 +0100, dennis@home wrote:
>
>> On 27/06/2013 22:10, Vir Campestris wrote:
>>> On 27/06/2013 11:03, mike wrote:
>>>> And I don't see why their methodology is right and mine is wrong.
>>>
>>> Nor do I.
>>>
>>> Let me work it backwards. There's a 4/10 chance of the first button you
>>> press being one of the combination ones, then 3/9, then 2/8, then 1/7.
>>>
>>> So your chance of getting it right is (4*3*2*1)/(10*9*7*8). That's 1 in
>>> 210.
>>>
>>> Andy
>>
>> I always set a five or six digit code to beat the ones that think they
>> only have four digit codes.
>
> The optimum would appear to be a 5 digit code - the odds go to 1 in 252.
> With a six digit code they go back to 1 in 210.
>

They don't unless the person knows its a six digit code.
If you don't know how long the code is you have 1024 possibles.

If they think its a four digit code their chances are zero if any other
length is tried.

Anyway even at 252 variants its probably more than a typical Yale
cylinder has and people don't worry about someone bringing a hundred
keys and trying each one which is probably quicker than trying all the
codes.

the main thing is to fit the keysafe where it can't be easily seen but
the person using it can't hide.
Don't fit them inside porches or rear gardens as nobody takes any notice
of a person "working" there.

[Dave Liquorice]

On Fri, 28 Jun 2013 01:21:49 -0700 (PDT), mike wrote:

> The 'numbers' don't come into play in the sense that each button (unlike
> a dial) can't represent 0 to 9; it can only represent on or off, 0 or 1,

> face up or face down. And you can repeat them ...

Repeat a button how? Once it's pressed it's pressed (or turn a card,
it's turned) and no longer available.

The odds for getting the combination by chance must surely be:

No buttons pressed you choose 1 from the 10 available, 4 of which
could be right, odds of getting picking a correct one 1:2.5.

Next choose 1 from the 9 available, 3 of which could be right, odds
of getting picking a correct one 1:3.

Next choose 1 from the 8 available, 2 of which could be right, odds
of getting picking a correct one 1:4.

Next choose 1 from the 7 available, 1 of which could be right, odds
of getting picking a correct one 1:7.

2.5 x 3 x 4 x 7 = 210

> I'm not saying I'm right and anyone else is wrong. I made the original
> posting and I'm questioning whether I'm right.

Same here, we need a real statistician/mathematician to give the
definitive proof.

> As Dave TMH has already pointed out, Keysafe gave a different number of
> total possible combinations to the one that I suggested. And I
> suggested why they might be right.

That's the other thing, maximum number of combinations given the
rules of 10 buttons, each button can only be used once, a 4 digit
code that can be entered in any order may not be the same as that
that could be indicated by the odds of entering the correct
combination by chance.

> I agree with you that probabilties are not particularly intuative. The
> Monty Hall problem was mentioned on here not so long ago and that's
> obviously quite contentious.

But proven, even if some very eminent mathematicians didn't believe
the proof...

--
Cheers
Dave.

[dochol...@gmail.com]

On Friday, June 28, 2013 2:58:14 PM UTC+1, Dave Liquorice wrote:
<snip>

> The odds for getting the combination by chance must surely be:
>
> No buttons pressed you choose 1 from the 10 available, 4 of which
> could be right, odds of getting picking a correct one 1:2.5.
>
> Next choose 1 from the 9 available, 3 of which could be right, odds
> of getting picking a correct one 1:3.
>
> Next choose 1 from the 8 available, 2 of which could be right, odds
> of getting picking a correct one 1:4.
>
> Next choose 1 from the 7 available, 1 of which could be right, odds
> of getting picking a correct one 1:7.
>
> 2.5 x 3 x 4 x 7 = 210
>

That agrees with the standard formula for picking 4 objects out of 10.
The formula for picking n objects out of m is m!/(n!.(m-n)!) (n! is n factorial).
Using that and adding up all the possible combinations then you do get 1024, as keysafe claim, though some of the combinations are probably not recommended!
It builds up like this:
no of ways of picking 0 buttons

[dochol...@gmail.com]

Damn - posted prematurely - to continue...
no of ways of picking 0 buttons 1
no of ways of picking 1 button 10
no of ways of picking 2 buttons 45
no of ways of picking 3 buttons 120
no of ways of picking 4 buttons 210
no of ways of picking 5 buttons 252
no of ways of picking 6 buttons will be the same as for 4, for fairly obvious reasons, and the same goes for 7 to 10 buttons.
Add all this up and you get 1024. I wouldn't recommend choosing 0 or 10 buttons as your combination, though - that's taking security by obscurity a bit too far!