Add 9/21 and 28/40
9/21 + 28/40 is 79/70.
Steps for adding fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 21 and 40 is 840
Next, find the equivalent fraction of both fractional numbers with denominator 840 - For the 1st fraction, since 21 × 40 = 840,
9/21 = 9 × 40/21 × 40 = 360/840 - Likewise, for the 2nd fraction, since 40 × 21 = 840,
28/40 = 28 × 21/40 × 21 = 588/840 - Add the two like fractions:
360/840 + 588/840 = 360 + 588/840 = 948/840 - 948/840 simplified gives 79/70
- So, 9/21 + 28/40 = 79/70
In mixed form: 19/70
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 18/21+28/40 9/21+56/40 9/42+28/40 9/21+28/80 27/21+28/40 9/21+84/40 9/63+28/40 45/21+28/40 63/21+28/40