Explain the advantages and disadvantages of using the LCM of the denominators.

Question

for adding and subtracting fractions, any common denominators will do.

Answer 1

The use of the LCM - Least Common Multiple - to make the denominators of fractions equal minimized the need to reduce the fractions once the addition/subtraction is completed.

 

E.g.,

 

1/2 + 1/3

30/60 + 20/60             Using 60 as CM, certainly not least

50/60                           combine like terms

5/6                               reduce

 

v.

 

1/2 + 1/3

3/6 + 2/6          LCM, 6

5/6                   combine