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What's my phone number?
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bazerko
May 10, 2012, 3:12:34 PM5/10/12
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I recently noticed that my (ten digit, US) phone number is the fourth
power of a prime number. I also noticed that each of the digits of the
prime number appear in my phone number, but not in the same order.
What's my phone number?
Background info: The first digit of a ten digit US phone numbers can
be anything but 0 or 1.
[The following number contains the answer, scrambled, so I won't lose
it. (It's not really my phone number, it's somebody in ... oops,
almost gave you a clue.) Extra credit if you demonstrate how to
unscramble it, 2149945771.]
power of a prime number. I also noticed that each of the digits of the
prime number appear in my phone number, but not in the same order.
What's my phone number?
Background info: The first digit of a ten digit US phone numbers can
be anything but 0 or 1.
[The following number contains the answer, scrambled, so I won't lose
it. (It's not really my phone number, it's somebody in ... oops,
almost gave you a clue.) Extra credit if you demonstrate how to
unscramble it, 2149945771.]
bazerko
May 10, 2012, 3:40:21 PM5/10/12
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Oops again. US phone numbers can't start with 9, either. But even if
they could, it wouldn't change the answer.
they could, it wouldn't change the answer.
Ilan Mayer
May 10, 2012, 5:30:17 PM5/10/12
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On May 10, 3:40 pm, bazerko <baze...@cox.net> wrote:
> Oops again. US phone numbers can't start with 9, either. But even if
> they could, it wouldn't change the answer.
SPOILER
> Oops again. US phone numbers can't start with 9, either. But even if
> they could, it wouldn't change the answer.
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The prime number must be between 211 and 316.
There are only 19 such prime numbers.
By trial and error the number is 241, and its 4th power is 3373402561.
Using 2149945771, add 1 to the 1st digit, 2 to the 2nd digit, etc.
modulo 10, to reach 3373402561.
Please reply to ilan dot mayer at hotmail dot com
__/\__
\ /
__/\\ //\__ Ilan Mayer
\ /
/__ __\ Toronto, Canada
/__ __\
||
bazerko
May 10, 2012, 6:14:27 PM5/10/12
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You got it! Both parts.
If that was too easy, here are some more, increasing in difficulty.
My phone number is an even prime number raised to an integer power.
The last digit of the prime is the same as the last digit of the phone
number. What's my number?
My phone number is an odd prime number raised to an integer power. The
last digit of the prime is the same as the last digit of the phone
number. What's my number?
My phone number is a prime number raised to an integer power. I live
in Toronto. (Same form of numbers for Toronto, which, for many
purposes, is not in the US. Its area codes are 226, 289, 416, 519,
647, 705,and 905) What's my number?
If that was too easy, here are some more, increasing in difficulty.
My phone number is an even prime number raised to an integer power.
The last digit of the prime is the same as the last digit of the phone
number. What's my number?
My phone number is an odd prime number raised to an integer power. The
last digit of the prime is the same as the last digit of the phone
number. What's my number?
My phone number is a prime number raised to an integer power. I live
in Toronto. (Same form of numbers for Toronto, which, for many
purposes, is not in the US. Its area codes are 226, 289, 416, 519,
647, 705,and 905) What's my number?
Ilan Mayer
May 11, 2012, 12:19:21 AM5/11/12
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The only odd prime number is 2
The only 10 digit power of 2 ending in 2 is 2^33 = 8589934592
Problem 2:
There are numerous solutions; here are some:
5^14 = 6103515625
11^9 = 2357947691
73^5 = 2073071593
79^5 = 3077056399
83^5 = 3939040643
89^5 = 5584059449
97^5 = 8587340257
Problem 3:
1609^3 = 4165509529
There are numerous solutions with power 2, e.g., 47563^2 = 2262238969.
Actually only 416 and 647 are Toronto area codes. The rest are for
areas outside Toronto.
alexy
May 16, 2012, 8:51:53 PM5/16/12
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bazerko <baz...@cox.net> wrote:
>Oops again. US phone numbers can't start with 9, either. But even if
>they could, it wouldn't change the answer.
Tell that so someone living in Memphis (area code 901), Jacksonville
>Oops again. US phone numbers can't start with 9, either. But even if
>they could, it wouldn't change the answer.
(area code 904), south Georgia (area code 912), ...
--
Alex -- Replace "nospam" with "mail" to reply by email. Checked infrequently.
Citizens for Carl Wasco
Jun 1, 2012, 4:46:59 PM6/1/12
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