Add 12/21 and 21/90
12/21 + 21/90 is 169/210.
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,
12/21 = 12 × 30/21 × 30 = 360/630 - Likewise, for the 2nd fraction, since 90 × 7 = 630,
21/90 = 21 × 7/90 × 7 = 147/630 - Add the two like fractions:
360/630 + 147/630 = 360 + 147/630 = 507/630 - 507/630 simplified gives 169/210
- So, 12/21 + 21/90 = 169/210
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 24/21+21/90 12/21+42/90 12/42+21/90 36/21+21/90 12/21+63/90 12/63+21/90 60/21+21/90 84/21+21/90