SOLUTION: the lcm of 84 and the n is 588 and their gcf is 28. What is n?

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Question 933548: the lcm of 84 and the n is 588 and their gcf is 28. What is n?
Answer by Theo(13342) About Me  (Show Source):
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the first number is 84
the second number is not known.
the least common multiple is 588
the greatest common factor is 28.

84 has to be equal to 28 * 3 because 84 / 28 = 3 and 28 is a factor of 84.

so we know that 84 = 28 * 3.

since 588 is a multiple of 84, then 588 / 84 = 7

so we know that 84 * 7 = 588 which simplifies to 28 * 3 * 7 = 588

since 588 is a multiple of our second number, and since 28 is a factor of our our second number, then we know that 28 * x = 588.

solve for x and we get x = 21

we get 28 * 21 = 588.

this can be simplified to 28 * 3 * 7 = 588.

our first number gets us 28 * 3 * 7 = 588

our second number gets us 28 * 3 * 7 = 588

our first number is 28 * 3 = 84

our second number must be 28 * 7 = 196.

our first numeber is 84.
our second number is 196.

the greatest common factor is 28 because 28 * 3 = 84 and 28 * 7 = 96.

the least common multiple is 588 because 84 * 7 = 588 and 196 * 3 = 588.

breaking both numbers down to their prime factors, we get:

84 = 4*7*3

196 = 4*7*7

common factors are 4*7 = 28

uncommon factors are 3 and 7 that are left after you strip out 4*7 from each.

least common multiple is therefore 3 * 196 and 7 * 84.