Add 42/21 and 90/81
1st number: 2 0/21, 2nd number: 1 9/81
42/21 + 90/81 is 28/9.
Steps for adding fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 21 and 81 is 567
Next, find the equivalent fraction of both fractional numbers with denominator 567 - For the 1st fraction, since 21 × 27 = 567,
42/21 = 42 × 27/21 × 27 = 1134/567 - Likewise, for the 2nd fraction, since 81 × 7 = 567,
90/81 = 90 × 7/81 × 7 = 630/567 - Add the two like fractions:
1134/567 + 630/567 = 1134 + 630/567 = 1764/567 - 1764/567 simplified gives 28/9
- So, 42/21 + 90/81 = 28/9
In mixed form: 31/9
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 84/21+90/81 42/63+90/81