Question

I have 20 oranges. What is the least number of oranges I need to take such that I can divide the oranges into groups of 6 or groups of 9 without leftovers?

• A. 12
• B. 15
• C. 18
• D. 9

Answer 1

The correct option is C 18

To find the least number of oranges I must find the LCM of the given numbers 6 and 9.

$\begin{array}{cc}3& 6,9\\ & 2,3\end{array}$

Since there are no common factors for 2 and 3 we cannot factorise it further.

Hence, the LCM of 6 and 9
= 3 × 2 × 3 = 18

We can pick a total of 18 oranges to divide them in groups of either 6 or 9 without leftovers.