Add 21/42 and 45/84
21/42 + 45/84 is 29/28.
Steps for adding fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 42 and 84 is 84
Next, find the equivalent fraction of both fractional numbers with denominator 84 - For the 1st fraction, since 42 × 2 = 84,
21/42 = 21 × 2/42 × 2 = 42/84 - Likewise, for the 2nd fraction, since 84 × 1 = 84,
45/84 = 45 × 1/84 × 1 = 45/84 - Add the two like fractions:
42/84 + 45/84 = 42 + 45/84 = 87/84 - 87/84 simplified gives 29/28
- So, 21/42 + 45/84 = 29/28
In mixed form: 11/28
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 21/42+90/84 21/84+45/84 63/42+45/84