Write down separately the prime and composite numbers less than 20.

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

Write down separately the prime and composite numbers less than 20.

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