Answers

Add 21/84 and 81/80

1^st number: 21/84, 2^nd number: 1 1/80

21/84 + 81/80 is 101/80.

Steps for adding fractions

1. Find the least common denominator or LCM of the two denominators:
   LCM of 84 and 80 is 1680
   
   Next, find the equivalent fraction of both fractional numbers with denominator 1680
2. For the 1st fraction, since 84 × 20 = 1680,
   21/84 = 21 × 20/84 × 20 = 420/1680
3. Likewise, for the 2nd fraction, since 80 × 21 = 1680,
   81/80 = 81 × 21/80 × 21 = 1701/1680
4. Add the two like fractions:
   420/1680 + 1701/1680 = 420 + 1701/1680 = 2121/1680
5. 2121/1680 simplified gives 101/80
6. So, 21/84 + 81/80 = 101/80
   In mixed form: 121/80

MathStep (Works offline)

Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad

Related: ⁴²/₈₄+⁸¹/₈₀ ⁶³/₈₄+⁸¹/₈₀

Add Fractions Calculator