Add 21/42 and 8/40
21/42 + 8/40 is 7/10.
Steps for adding fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 42 and 40 is 840
Next, find the equivalent fraction of both fractional numbers with denominator 840 - For the 1st fraction, since 42 × 20 = 840,
21/42 = 21 × 20/42 × 20 = 420/840 - Likewise, for the 2nd fraction, since 40 × 21 = 840,
8/40 = 8 × 21/40 × 21 = 168/840 - Add the two like fractions:
420/840 + 168/840 = 420 + 168/840 = 588/840 - 588/840 simplified gives 7/10
- So, 21/42 + 8/40 = 7/10
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 21/42+16/40 21/84+8/40 21/42+8/80 63/42+8/40 21/42+24/40 21/42+56/40