Question

How many prime numbers are less than $20$?

Answer 1

Solve for prime numbers

A prime number is a natural number greater than $1$ with exactly two factors that is $1$ and the number itself. Consider an example $7$, It has two factors $1,7$

$\therefore$Prime number less than $20$are : $2,3,5,7,11,13,17,19$

Hence there are $8$ Prime numbers less than $20$