If you wanted to find the difference of 6/25 - 4/5 , what common denominator should you choose? Why?
You can calculate like that:
6 / 25 - 4 / 5 = 0.24 - 0.8 = - 0.56 =
- 56 / 100 = - 4 • 14 / 4 • 25 =
- 14 / 25
But, you also calculate like this.
Least Common Denominator (LCD) of 6 / 25 and 4 / 5 is 25
6 / 25 - 4 / 5 = 6 / 25 - 4 • 5 / 5 • 5 =
6 / 25 - 20 / 25 = - 14 / 25
The reason for choosing the lowest common denominator is that it is easier.