Add 40/80 and 42/21
1st number: 40/80, 2nd number: 2 0/21
40/80 + 42/21 is 5/2.
Steps for adding fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 80 and 21 is 1680
Next, find the equivalent fraction of both fractional numbers with denominator 1680 - For the 1st fraction, since 80 × 21 = 1680,
40/80 = 40 × 21/80 × 21 = 840/1680 - Likewise, for the 2nd fraction, since 21 × 80 = 1680,
42/21 = 42 × 80/21 × 80 = 3360/1680 - Add the two like fractions:
840/1680 + 3360/1680 = 840 + 3360/1680 = 4200/1680 - 4200/1680 simplified gives 5/2
- So, 40/80 + 42/21 = 5/2
In mixed form: 21/2
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 40/80+84/21 40/80+42/63