Add 20/12 and 84/21
1st number: 1 8/12, 2nd number: 4 0/21
20/12 + 84/21 is 17/3.
Steps for adding fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 12 and 21 is 84
Next, find the equivalent fraction of both fractional numbers with denominator 84 - For the 1st fraction, since 12 × 7 = 84,
20/12 = 20 × 7/12 × 7 = 140/84 - Likewise, for the 2nd fraction, since 21 × 4 = 84,
84/21 = 84 × 4/21 × 4 = 336/84 - Add the two like fractions:
140/84 + 336/84 = 140 + 336/84 = 476/84 - 476/84 simplified gives 17/3
- So, 20/12 + 84/21 = 17/3
In mixed form: 52/3
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 40/12+84/21 20/24+84/21 20/12+84/42 60/12+84/21 20/36+84/21 20/12+84/63 20/60+84/21 20/84+84/21