Add 70/90 and 80/21
1st number: 70/90, 2nd number: 3 17/21
70/90 + 80/21 is 289/63.
Steps for adding fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 90 and 21 is 630
Next, find the equivalent fraction of both fractional numbers with denominator 630 - For the 1st fraction, since 90 × 7 = 630,
70/90 = 70 × 7/90 × 7 = 490/630 - Likewise, for the 2nd fraction, since 21 × 30 = 630,
80/21 = 80 × 30/21 × 30 = 2400/630 - Add the two like fractions:
490/630 + 2400/630 = 490 + 2400/630 = 2890/630 - 2890/630 simplified gives 289/63
- So, 70/90 + 80/21 = 289/63
In mixed form: 437/63
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 70/90+80/42 70/90+80/63