What is the procedure for finding the least common denominator?

Answer 1

1 - Break down each denominator into prime factors. For example, let's say your denominators are 45, 18 and 27.

45 = 32 x 5

18 = 2 x 32

27 = 33

2 - Find the greatest number of each factor needed by all the denominators.

If it helps, you can rewrite the prime factorization like this:

45 = 20 x 32 x 51

18 = 21 x 32 x 50

27 = 20 x 33 x 50

Anything to the zero power equals one. When you line them up like that, it's easier to see that you need one 2, three 3's and one 5.

3 - Multiply them together; that's your LCD.

2 x 33 x 5 = 2 x 27 x 5 = 270

Answer 2

Example: 1/30 and 1/42

Factor them.

2 x 3 x 5 = 30

2 x 3 x 7 = 42

Select the highest amount of each factor.

2 x 3 x 5 x 7 = 210, the LCD