Add 21/30 and 3/18
21/30 + 3/18 is 13/15.
Steps for adding fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 30 and 18 is 90
Next, find the equivalent fraction of both fractional numbers with denominator 90 - For the 1st fraction, since 30 × 3 = 90,
21/30 = 21 × 3/30 × 3 = 63/90 - Likewise, for the 2nd fraction, since 18 × 5 = 90,
3/18 = 3 × 5/18 × 5 = 15/90 - Add the two like fractions:
63/90 + 15/90 = 63 + 15/90 = 78/90 - 78/90 simplified gives 13/15
- So, 21/30 + 3/18 = 13/15
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 42/30+3/18 21/30+6/18 21/60+3/18 21/30+3/36 63/30+3/18 21/30+9/18 21/90+3/18 21/30+3/54 21/30+15/18 21/30+3/90 21/30+21/18