Scott T. answered • 10/19/12

Math and Science Tutoring from an MIT Masters in Engineering

Hi Dayln,

To find the least common denominator, first you should do a prime factorization on each denominator you are comparing.

That may sound scary, but it's not too bad.

24 = 2*2*2*3

12 = 2*2*3

28 = 2*2*7

The least common denominator can be found by choosing a set of prime factors that includes all of the above numbers.

In this case, choose 2*2*2*3*7, because each of the prime factors above are included in this set of numbers.

Then just multiply 2*2*2*3*7 = 168

168 is the least common denominator - it's the number that all the other denominators will divide into without a remainder.

Please comment if you need more explanation, or if you're not familiar with prime factorization.

Hope it helps!