Add 21/42 and 84/90
21/42 + 84/90 is 43/30.
Steps for adding fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 42 and 90 is 630
Next, find the equivalent fraction of both fractional numbers with denominator 630 - For the 1st fraction, since 42 × 15 = 630,
21/42 = 21 × 15/42 × 15 = 315/630 - Likewise, for the 2nd fraction, since 90 × 7 = 630,
84/90 = 84 × 7/90 × 7 = 588/630 - Add the two like fractions:
315/630 + 588/630 = 315 + 588/630 = 903/630 - 903/630 simplified gives 43/30
- So, 21/42 + 84/90 = 43/30
In mixed form: 113/30
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 21/84+84/90 63/42+84/90