Add 21/84 and 18/40
21/84 + 18/40 is 7/10.
Steps for adding fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 84 and 40 is 840
Next, find the equivalent fraction of both fractional numbers with denominator 840 - For the 1st fraction, since 84 × 10 = 840,
21/84 = 21 × 10/84 × 10 = 210/840 - Likewise, for the 2nd fraction, since 40 × 21 = 840,
18/40 = 18 × 21/40 × 21 = 378/840 - Add the two like fractions:
210/840 + 378/840 = 210 + 378/840 = 588/840 - 588/840 simplified gives 7/10
- So, 21/84 + 18/40 = 7/10
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 42/84+18/40 21/84+36/40 21/84+18/80 63/84+18/40 21/84+54/40 21/84+90/40