question_answer

The greatest four digit number which is exactly divisible by each one of the numbers 12, 18, 21 and 28 is

A)  9828             

B)  9288

C)  9882             

D)       9928

Correct Answer: A

Solution :

  

2	12,	18,	21,	28
2	6,	9,	21,	14
3	3,	9,	21,	7
7	1,	3,	7,	7
	1,	3,	1,	1,

\[\therefore \]   LCM \[=2\times 2\times 3\times 3\times 7=252\] The largest 4-digit number = 9999             \[\therefore \]  Required number \[=9999-171=9828\]