Question

$20$ is written as the product of primes as :

• A. $2\times 5$
• B. $2\times 2\times 3\times 5$
• C. $2\times 2\times 5$
• D. $2\times 2\times 3$

Answer 1

The correct option is C $2\times 2\times 5$

To write a number as product of its primes, we divide it by various prime numbers $2,3,5,7$ etc one by one and check by which prime numbers it is divisible with and how many times.

Hence, $20=2\times 10=2\times 2\times 5$