What will be the least number which when doubled will be exactly divisible by 12, 18, 21 and 30?  Choices:
A) 228	B) 630	C) 998	D) 267	E) 212
L.C.M of 12, 18, 21, 30   = 2 * 3 * 2 * 3 * 7 * 5= 
<gadget id="calculator">2 * 3 * 2 * 3 * 7 * 5</gadget>
<output>1_260</output>
1260   Required number= 1260/2= 
<gadget id="calculator">1260/2</gadget>
<output>630</output>
630.   Answer:630
<result>B</result>
What will be the least number which when doubled will be exactly divisible by 12, 18, 21 and 30?