Find the common factors of 15 and 18.  Choose the most appropriate option.
A) 50  B) 55  C) 60  D) 70  E) 90

Rationale: first of all we need to find the prime factors of 15 and 18 15 = 5 x 3 18 = 3 x 3 x 2 lcm is the product of highest exponent of all the factors . lcm ( 15,18 ) = 5 x 3 ^ 2 x 2 = 90 answer : 90
Answer: E