Make them the same before you add or subtract!
Before adding or subtracting fractions, the denominators must be the same. When denominators are different (unlike), we find the Least Common Denominator (LCD) â the smallest number that both denominators divide into evenly â and rewrite each fraction.
Adding Unlike Fractions
Denominators 3 and 4: List multiples of 3: 3, 6, 9, 12, 15... List multiples of 4: 4, 8, 12, 16... The LCD is 12. Multiply 1/3 by 4/4 and 1/4 by 3/3.
Multiplying the top and bottom by the same number creates an equivalent fraction â you are multiplying by 1!
Remember This!
If you can't find the LCD quickly, just use the product of the two denominators. You might need to simplify at the end, but it always works.
What is ÂŊ + â ?