Find the least number which when divided by 16, 18 and 20

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Find the least number which when divided by 16, 18 and 20 leaves a remainder 4 in each case, but is completely divisible by 7.

1. 2884
2. 2256
3. 865
4. 3332
5. None of the above

Correct Option: A

LCM of 16, 18 and 20 = 720
∴ Required number = 720k + 4
Where, k is a natural number to be divisible by 7, (720 k + 4) will be a multiple of 7.
Smallest value of k = 4
∴ Required number = 720 x 4 + 4 = 2884