Add 18/20 and 15/21
18/20 + 15/21 is 113/70.
Steps for adding fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 20 and 21 is 420
Next, find the equivalent fraction of both fractional numbers with denominator 420 - For the 1st fraction, since 20 × 21 = 420,
18/20 = 18 × 21/20 × 21 = 378/420 - Likewise, for the 2nd fraction, since 21 × 20 = 420,
15/21 = 15 × 20/21 × 20 = 300/420 - Add the two like fractions:
378/420 + 300/420 = 378 + 300/420 = 678/420 - 678/420 simplified gives 113/70
- So, 18/20 + 15/21 = 113/70
In mixed form: 143/70
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 36/20+15/21 18/20+30/21 18/40+15/21 18/20+15/42 54/20+15/21 18/20+45/21 18/60+15/21 18/20+15/63 90/20+15/21 18/20+75/21