Add 72/40 and 70/21
1st number: 1 32/40, 2nd number: 3 7/21
72/40 + 70/21 is 77/15.
Steps for adding fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 40 and 21 is 840
Next, find the equivalent fraction of both fractional numbers with denominator 840 - For the 1st fraction, since 40 × 21 = 840,
72/40 = 72 × 21/40 × 21 = 1512/840 - Likewise, for the 2nd fraction, since 21 × 40 = 840,
70/21 = 70 × 40/21 × 40 = 2800/840 - Add the two like fractions:
1512/840 + 2800/840 = 1512 + 2800/840 = 4312/840 - 4312/840 simplified gives 77/15
- So, 72/40 + 70/21 = 77/15
In mixed form: 52/15
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 72/80+70/21 72/40+70/42 72/40+70/63