Question

Which is the least number which when doubled will be exactly divisible by 12, 18, 21 and 30?

Answer 1

L.C.M. of 12,18,21,30 is 1260.
when we divide it by 2 it will become 630.
so the least no. which is divisible by these no. is 630.
we divide it by 2 because the no. is doubled.

Answer 2

$12 => 2 × 2 × 3$

$18 =>2 × 3 × 3$

$21 => 3 × 7$

$30 => 2 × 3 × 5$

L.C.M. of $12, 18, 21,30 = 2 × 3 × 2 × 3 × 7 × 5 = 1260$

Required number$= 1260/2</p><p> = 630$ ANSWER

HOPE SO IT IS HELPFUL..PLS FOLLOW ME..✌️❣️..