Add 15/90 and 7/21
15/90 + 7/21 is 1/2.
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,
7/21 = 7 × 30/21 × 30 = 210/630 - Add the two like fractions:
105/630 + 210/630 = 105 + 210/630 = 315/630 - 315/630 simplified gives 1/2
- So, 15/90 + 7/21 = 1/2
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 30/90+7/21 15/90+14/21 15/90+7/42 45/90+7/21 15/90+7/63 75/90+7/21 15/90+35/21 15/90+49/21