random number picker

[Paul Ferris]

Is it possible to have Numbas randomly select say 6 number but restricting to just ONE being prime?  I am trying to write a question ask student select the PRIME number from a list.  Thanks.

[Ulrich Goertz]

Here is one way to do this: https://numbas.mathcentre.ac.uk/question/179705/find-the-prime/

In that question, Numbas chooses one random entry from a list of primes, and 5 random entries from a list of non-primes, and presents these 6 numbers in ascending order.

Another approach for this kind of problem could be to choose 6 random numbers and then use "Variable testing" to ensure that the condition that exactly one is a prime is met, but in this particular situation this would be more complicated and compute-intensive.

Best regards, Ulrich

[Ben Brawn]

I would take a list of primes off the internet and a separate list of composite numbers. And make variables like this using those lists. 

 

Prime = random([2,3,5,7…])

Composites = shuffle([4,6,8,…])[0..5]

Options = shuffle([prime]+composites)

Then mark correct if their answer is equal to the variable Prime. 

Let me know if something doesn’t make sense

On Thu, 4 Sep 2025 at 1:38 am, Paul Ferris <paul.fe...@gmail.com> wrote:

Is it possible to have Numbas randomly select say 6 number but restricting to just ONE being prime?  I am trying to write a question ask student select the PRIME number from a list.  Thanks.

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