Question

If 31z5 is multiple of 9,where z is a digit,what is the the value of z?
you will find that that there are 2 answers for the last problem.why is this so

Answer 1

Step-by-step explanation:

Playing with Numbers

∵ 31z5 is divisible by 9. ∴ (9 + z) must be equal to 0, or 9 or 18 or 27, ... But z is a digit. ∴ 9 + z = 0 or 9 + z= 18 If 9 + z = 0, then z = 0 and if 9 + z = 18, then z = 9.