Add 21/40 and 12/90
21/40 + 12/90 is 79/120.
Steps for adding fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 40 and 90 is 360
Next, find the equivalent fraction of both fractional numbers with denominator 360 - For the 1st fraction, since 40 × 9 = 360,
21/40 = 21 × 9/40 × 9 = 189/360 - Likewise, for the 2nd fraction, since 90 × 4 = 360,
12/90 = 12 × 4/90 × 4 = 48/360 - Add the two like fractions:
189/360 + 48/360 = 189 + 48/360 = 237/360 - 237/360 simplified gives 79/120
- So, 21/40 + 12/90 = 79/120
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 42/40+12/90 21/40+24/90 21/80+12/90 63/40+12/90 21/40+36/90 21/40+60/90 21/40+84/90