# Math Help - perfect square

1. ## perfect square

What is the smallest positive integer which multiplied by 40 gives a perfect square?
(A) 2 (B) 5 (C) 20 (D) 40 (E) None of these

2. Originally Posted by sri340
What is the smallest positive integer which multiplied by 40 gives a perfect square?
(A) 2 (B) 5 (C) 20 (D) 40 (E) None of these
10, but in the given choices it is missing. So the choice is.......?

3. Originally Posted by sri340
What is the smallest positive integer which multiplied by 40 gives a perfect square?
(A) 2 (B) 5 (C) 20 (D) 40 (E) None of these

$40=2^3\cdot 5\Longrightarrow$ you have to make both 2 and 5 to have even powers, so...

Tonio