What is the greatest common divisor of 90, 1020 and 2340? 

Correct option is A

Given:

The numbers are 90, 1020, and 2340.

Concept Used:
To find the Greatest Common Divisor (GCD) or Highest Common Factor (HCF) of multiple numbers,

we use their prime factorization and find the product of the lowest powers of common prime factors.

Solution:

Prime factorization of each:

90 = 2$$\times 3^2 \times 5$$​​

1020 =$$2^2 \times 3 \times 5 \times 17$$​​

2340 =$$2^2 \times 3^2 \times 5 \times 13$$​​

Take the common prime factors with the lowest powers:

​$$2^1$$​ (minimum power of 2)

​$$3^1$$​​

​$$5^1$$​​

So,

HCF = 2 × 3 × 5 = 30