Question

How do you know that 5, 7, 8, 9, 10, and 11 are not factors of 12?

Answer 1

Answer :

Factors of 12 are

`1 * 12 \\ 2 * 6 \\ 3 * 4.`

1. 5 multiplied by any number can never give 12 . Multiples of 5 are
2. 
   `5 \: 10 \: 15 \: 20`
3. 7 multiples are
4. 
   `7 \: 14 \: 21`
5. Same applies for all the listed numbers