What is the smallest positive perfect square that is divisible by 4, 10, and 18?
Options
A) 900
B) 1,600
C) 2,500
D) 3,600
E) 4,900

Rationale: the number needs to be divisible by 2 ^ 2 , 2 * 5 , and 2 * 3 ^ 2 . the smallest such perfect square is 2 ^ 2 * 3 ^ 2 * 5 ^ 2 = 900 the answer is a .
Answer: A