For Fraction Addition and Subtraction - Which method is best?


Well-known member
Using LCM or the formulas like:

\(\displaystyle \dfrac{a}{b} + \dfrac{c}{d} \)

\(\displaystyle \dfrac{(a)(d) + (b)(c)}{(b)(d)} \) etc.. (Subtraction one has a minus instead of a plus.)

The speed at doing LCM depends on how good you are finding LCM - and that could be as fast as someone knowing the formula given in this post.


La Villa Strangiato
Math Helper
It's hard to say which is best...I think it depends on the actual expression.