Question

Find the smallest number from which 3 is to be subtracted so that the difference is exactly divisible 18,24,36

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Answer 1

72

Explanation:

look at the prime factors of each number.

18 = 2*3^2

24 = 2^3*3

36 = 2^2*3^2

The most factors of 2 in any of these numbers is 3: 2^3

The most factors of 3 in any of these numbers is 2: 3^2

2^3*3^2 is 8*9 or 72.

72 is the lowest number exactly divisible by 18, 24, and 36.