Question

If the ones digit in a two-digit number is even, the number is a composite number. Which odd ones digit also tells you the number must be a compositenumber? Explain.

Answer 1

Okay, here we have this:

Considering that a composite number is a number that is not prime, the only number one of the units that tells us that a two-digit number is composed is 5, since every number ending in 5 is a multiple of 5.