Question

The least number which is exactly divisible by 20, 30 and 40 is ____.

• A. 100
• B. 120
• C. 180
• D. 150

Answer 1

The correct option is B 120

To find the least number that will be exactly divisible by 20, 30 and 60, find the LCM.

$\begin{array}{cc}2& 20,30,40\\ 2& 10,15,20\\ 5& 5,15,10\\ 3& 1,3,2\\ 2& 1,1,2\\ & 1,1,1\end{array}$
LCM = 2 × 2 × 5 × 3 × 2
=120