Add 90/21 and 9/20
1st number: 4 6/21, 2nd number: 9/20
90/21 + 9/20 is 663/140.
Steps for adding fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 21 and 20 is 420
Next, find the equivalent fraction of both fractional numbers with denominator 420 - For the 1st fraction, since 21 × 20 = 420,
90/21 = 90 × 20/21 × 20 = 1800/420 - Likewise, for the 2nd fraction, since 20 × 21 = 420,
9/20 = 9 × 21/20 × 21 = 189/420 - Add the two like fractions:
1800/420 + 189/420 = 1800 + 189/420 = 1989/420 - 1989/420 simplified gives 663/140
- So, 90/21 + 9/20 = 663/140
In mixed form: 4103/140
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 90/21+18/20 90/42+9/20 90/21+9/40 90/21+27/20 90/63+9/20 90/21+9/60 90/21+45/20 90/21+63/20