A group of friends share a bill for £13.69 equally between them.

Question

how many were in the group?

Answer 1

1369 = 37 * 37
37 is a prime number
so
37 people paid .37 each

Answer 2

How I found out :

http://www.mathwarehouse.com/arithmetic/numbers/prime-number/prime-factorization.php?number=1369