Question

List down separately all the prime numbers and composite numbers less than 20.

Answer 1

The numbers other than 1 whose only factors are 1 and the number itself are called Prime numbers.

Prime numbers less than 20: 2, 3, 5, 7, 11, 13, 17, 19.

Numbers having more than two factors are called Composite numbers.

Composite numbers less than 20: 4, 6, 8, 9, 10, 12, 14, 15, 16, 18.

Note: Whole numbers which are not composite are prime numbers and vice versa.