Question

Find the smallest square number divisible by 6,9 and 15

Answer 1

$<u>Step 1</u>$ :- Find the LCM of 6, 9 and 15

6 = 3 × 2

9 = 3 × 3

15 = 5 × 3


Here, only 5 and 2 are not in pairs.

LCM = 90



$<u>Step 2</u>$ :- Multiply the numbers which are not in pair to the LCM


=> 90 × 2 × 5 = 900



$\therefore{}$ The square number is 900



• 900 is the square of 30

Answer 2

Find  the L.C.M. of  6,9,15.

$\begin{array}{@{}l|l@{}}\\2&6,9,15\\\cline{2-2}\\3&3,9,15\\\cline{2-2}\\3& 1,3,5\\\cline{2-2}\\5&1,1,5\\\cline{2-2}\\&1,1,1\\\end{array}\\\\\\L.C.M.=2\times3\times3\times5=90\\\\\text{Since,Pair of 5 and 2 is not there}\\\\Hence,\\\\\text{That smallest square number divisible by 6,9,15}=90\times2\times5=900\\\\\textbf{Which is the square of 30}$