Question

Find a least number which is exactly divisible by 18,24,36,42 when 6 is subtracted.

Answer 1

After subtraction you will get 12,18,30 and 36

now as you can see all of them are multiple of 6 so they all will have 2*3 as common factor

so answer is 6

Answer 2

first take hcf of numbers then add 6 to the HCF.

your answer is 12