In adding and subtracting fractions with unlike denominators, you have to get a least common denominator which is exactly like the least common multiple it just so happens to be in the denominator.

Learn how to perform calculations to add fractions with BBC Bitesize Maths. For students between the ages of 11 and 14.

Another sticking point for many students is adding fractions with different denominators—for example, coming up with 11/12 when asked to add 3/5 and 8/7.