Question

The number of unique prime factors of 420 are
1. 2
2. 3
3. 4
4. 5

Answer 1

Correct Answer - Option 3 : 4

Given:

420

Concept used:

Prime number:- The number which is divisible by 1 and itself. For example 2, 3, 5, etc

1 is not a prime number

Calculation:

Factors of 420 = 2² × 3¹ × 5¹ × 7¹

The prime factors of 420 are 2, 3, 5 and 7

∴ The total number of unique prime factors of 420 is 4 ie (2, 3, 5 and 7)