Add 18/20 and 20/21
18/20 + 20/21 is 389/210.
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,
20/21 = 20 × 20/21 × 20 = 400/420 - Add the two like fractions:
378/420 + 400/420 = 378 + 400/420 = 778/420 - 778/420 simplified gives 389/210
- So, 18/20 + 20/21 = 389/210
In mixed form: 1179/210
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 36/20+20/21 18/20+40/21 18/40+20/21 18/20+20/42 54/20+20/21 18/20+60/21 18/60+20/21 18/20+20/63 90/20+20/21