Add 21/90 and 15/70
21/90 + 15/70 is 47/105.
Steps for adding fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 90 and 70 is 630
Next, find the equivalent fraction of both fractional numbers with denominator 630 - For the 1st fraction, since 90 × 7 = 630,
21/90 = 21 × 7/90 × 7 = 147/630 - Likewise, for the 2nd fraction, since 70 × 9 = 630,
15/70 = 15 × 9/70 × 9 = 135/630 - Add the two like fractions:
147/630 + 135/630 = 147 + 135/630 = 282/630 - 282/630 simplified gives 47/105
- So, 21/90 + 15/70 = 47/105
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 42/90+15/70 21/90+30/70 63/90+15/70 21/90+45/70 21/90+75/70