Add 72/18 and 36/21
1st number: 4 0/18, 2nd number: 1 15/21
72/18 + 36/21 is 40/7.
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,
36/21 = 36 × 6/21 × 6 = 216/126 - Add the two like fractions:
504/126 + 216/126 = 504 + 216/126 = 720/126 - 720/126 simplified gives 40/7
- So, 72/18 + 36/21 = 40/7
In mixed form: 55/7
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 72/18+72/21 72/36+36/21 72/18+36/42 72/54+36/21 72/18+36/63 72/90+36/21