Question

Least no. Which when doubled become exactly divisible by 9 15 21 30

Answer 1

Answer:

First, take the LCM of 9, 15, 21 & 30.

LCM :-

9 = 3×3

15 = 3×5

21 = 3×7

30 = 2×3×5

LCM = 3×3×5×7×2×5 = 630

Now, half of the LCM is your required number. Because when it will be doubled it will give you the LCM of 9,15,21,30 which is the least value divisible by 9,15,21,30.

So number is 630÷2 = 315