How can you know if 6 is a factor of 78?

Answer 1

For a number to be divisible by 6, it has to be divisible by 2 and 3, because 2*3=6.In other words, we could divide the number we're factorising (78) by the prime factors of the number we're testing (6, which is 2*3).

We start by dividing by 2, because we know 78 is even: 78/2=39.

Then, we divide the new number by the other prime factor - 3.

39/3=13

13 is a whole number with no remainders, therefore we can say that 78 is divisible by 6, and therefore 6 is a factor of 78. (6*13=78)