Add 21/70 and 18/42
21/70 + 18/42 is 51/70.
Steps for adding fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 70 and 42 is 210
Next, find the equivalent fraction of both fractional numbers with denominator 210 - For the 1st fraction, since 70 × 3 = 210,
21/70 = 21 × 3/70 × 3 = 63/210 - Likewise, for the 2nd fraction, since 42 × 5 = 210,
18/42 = 18 × 5/42 × 5 = 90/210 - Add the two like fractions:
63/210 + 90/210 = 63 + 90/210 = 153/210 - 153/210 simplified gives 51/70
- So, 21/70 + 18/42 = 51/70
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 42/70+18/42 21/70+36/42 21/70+18/84 63/70+18/42 21/70+54/42 21/70+90/42