The greatest four digit number which is exactly divisible

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

1. 9828
2. 9288
3. 9882
4. 9928

Correct Option: A

First of all , we find the LCM of 12 , 18 , 21 and 28

∴ LCM = 2 × 2 × 3 × 3 × 7 = 252
The largest 4-digit number = 9999

Here , Remainder = 171
∴ Required number = The largest 4-digit number - Remainder
Hence , Required number = 9999 – 171 = 9828