Add 21/63 and 20/70
21/63 + 20/70 is 13/21.
Steps for adding fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 63 and 70 is 630
Next, find the equivalent fraction of both fractional numbers with denominator 630 - For the 1st fraction, since 63 × 10 = 630,
21/63 = 21 × 10/63 × 10 = 210/630 - Likewise, for the 2nd fraction, since 70 × 9 = 630,
20/70 = 20 × 9/70 × 9 = 180/630 - Add the two like fractions:
210/630 + 180/630 = 210 + 180/630 = 390/630 - 390/630 simplified gives 13/21
- So, 21/63 + 20/70 = 13/21
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 42/63+20/70 21/63+40/70 21/63+60/70