Question

Factorise natural numbers from 11 to 20 to discover which numbers are prime and which are composite .

Answer 1

11, 13, 15, 17, 19 can be divided evenly by 1 or the number itself hence they are prime numbers.

12 can be divided evenly by 1, 2, 3 and 12

14 can be divided evenly by 1, 7 and 14

16 can be divided evenly by 1, 2, 4, 8 and 16

18 can be divided evenly by 1, 2, 3, 6, 9 and 18

So, they are composite numbers.