Add 12/45 and 20/21
12/45 + 20/21 is 128/105.
Steps for adding fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 45 and 21 is 315
Next, find the equivalent fraction of both fractional numbers with denominator 315 - For the 1st fraction, since 45 × 7 = 315,
12/45 = 12 × 7/45 × 7 = 84/315 - Likewise, for the 2nd fraction, since 21 × 15 = 315,
20/21 = 20 × 15/21 × 15 = 300/315 - Add the two like fractions:
84/315 + 300/315 = 84 + 300/315 = 384/315 - 384/315 simplified gives 128/105
- So, 12/45 + 20/21 = 128/105
In mixed form: 123/105
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 24/45+20/21 12/45+40/21 12/90+20/21 12/45+20/42 36/45+20/21 12/45+60/21 12/45+20/63 60/45+20/21 84/45+20/21