Add 21/81 and 18/20
21/81 + 18/20 is 313/270.
Steps for adding fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 81 and 20 is 1620
Next, find the equivalent fraction of both fractional numbers with denominator 1620 - For the 1st fraction, since 81 × 20 = 1620,
21/81 = 21 × 20/81 × 20 = 420/1620 - Likewise, for the 2nd fraction, since 20 × 81 = 1620,
18/20 = 18 × 81/20 × 81 = 1458/1620 - Add the two like fractions:
420/1620 + 1458/1620 = 420 + 1458/1620 = 1878/1620 - 1878/1620 simplified gives 313/270
- So, 21/81 + 18/20 = 313/270
In mixed form: 143/270
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 42/81+18/20 21/81+36/20 21/81+18/40 63/81+18/20 21/81+54/20 21/81+18/60 21/81+90/20