Which is the least number which when double will be exactly divisible by 12, 18, 21 and 30?
[A]196
[B]630
[C]1260
[D]2520

630
The LCM of 12, 18, 21, 30 is 1260.
∴ The required Number =
= \frac{1260}{2} = 630
Hence option [B] is correct answer.