Add 81/21 and 18/90
1st number: 3 18/21, 2nd number: 18/90
81/21 + 18/90 is 142/35.
Steps for adding fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 21 and 90 is 630
Next, find the equivalent fraction of both fractional numbers with denominator 630 - For the 1st fraction, since 21 × 30 = 630,
81/21 = 81 × 30/21 × 30 = 2430/630 - Likewise, for the 2nd fraction, since 90 × 7 = 630,
18/90 = 18 × 7/90 × 7 = 126/630 - Add the two like fractions:
2430/630 + 126/630 = 2430 + 126/630 = 2556/630 - 2556/630 simplified gives 142/35
- So, 81/21 + 18/90 = 142/35
In mixed form: 42/35
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 81/21+36/90 81/42+18/90 81/21+54/90 81/63+18/90