Add 21/70 and 4/90
21/70 + 4/90 is 31/90.
Steps for adding fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 70 and 90 is 630
Next, find the equivalent fraction of both fractional numbers with denominator 630 - For the 1st fraction, since 70 × 9 = 630,
21/70 = 21 × 9/70 × 9 = 189/630 - Likewise, for the 2nd fraction, since 90 × 7 = 630,
4/90 = 4 × 7/90 × 7 = 28/630 - Add the two like fractions:
189/630 + 28/630 = 189 + 28/630 = 217/630 - 217/630 simplified gives 31/90
- So, 21/70 + 4/90 = 31/90
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 42/70+4/90 21/70+8/90 63/70+4/90 21/70+12/90 21/70+20/90 21/70+28/90