Add 15/90 and 28/21
1st number: 15/90, 2nd number: 1 7/21
15/90 + 28/21 is 3/2.
Steps for adding fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 90 and 21 is 630
Next, find the equivalent fraction of both fractional numbers with denominator 630 - For the 1st fraction, since 90 × 7 = 630,
15/90 = 15 × 7/90 × 7 = 105/630 - Likewise, for the 2nd fraction, since 21 × 30 = 630,
28/21 = 28 × 30/21 × 30 = 840/630 - Add the two like fractions:
105/630 + 840/630 = 105 + 840/630 = 945/630 - 945/630 simplified gives 3/2
- So, 15/90 + 28/21 = 3/2
In mixed form: 11/2
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 30/90+28/21 15/90+56/21 15/90+28/42 45/90+28/21 15/90+84/21 15/90+28/63 75/90+28/21