Question

What is the GCD of the following ? 90,150,225

• A. 5
• B. 10
• C. 15
• D. 50

Answer 1

The correct option is C

15

Let us write numbers 90,150 and 225 as the product of then prime factors
$90=2\times 3\times 3\times 5150=2\times 3\times 5\times 5225=3\times 3\times 5\times 5$
Here, 3 and 5 are common prime factors of all the given numbers.
Hence, GCD =$3\times 5=15$