Add 15/21 and 12/90
15/21 + 12/90 is 89/105.
Steps for adding fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 21 and 90 is 630
Next, find the equivalent fraction of both fractional numbers with denominator 630 - For the 1st fraction, since 21 × 30 = 630,
15/21 = 15 × 30/21 × 30 = 450/630 - Likewise, for the 2nd fraction, since 90 × 7 = 630,
12/90 = 12 × 7/90 × 7 = 84/630 - Add the two like fractions:
450/630 + 84/630 = 450 + 84/630 = 534/630 - 534/630 simplified gives 89/105
- So, 15/21 + 12/90 = 89/105
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 30/21+12/90 15/21+24/90 15/42+12/90 45/21+12/90 15/21+36/90 15/63+12/90 75/21+12/90 15/21+60/90 15/21+84/90