Add 72/18 and 30/21
1st number: 4 0/18, 2nd number: 1 9/21
72/18 + 30/21 is 38/7.
Steps for adding fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 18 and 21 is 126
Next, find the equivalent fraction of both fractional numbers with denominator 126 - For the 1st fraction, since 18 × 7 = 126,
72/18 = 72 × 7/18 × 7 = 504/126 - Likewise, for the 2nd fraction, since 21 × 6 = 126,
30/21 = 30 × 6/21 × 6 = 180/126 - Add the two like fractions:
504/126 + 180/126 = 504 + 180/126 = 684/126 - 684/126 simplified gives 38/7
- So, 72/18 + 30/21 = 38/7
In mixed form: 53/7
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 72/18+60/21 72/36+30/21 72/18+30/42 72/18+90/21 72/54+30/21 72/18+30/63 72/90+30/21