Add 15/90 and 8/21
15/90 + 8/21 is 23/42.
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,
8/21 = 8 × 30/21 × 30 = 240/630 - Add the two like fractions:
105/630 + 240/630 = 105 + 240/630 = 345/630 - 345/630 simplified gives 23/42
- So, 15/90 + 8/21 = 23/42
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 30/90+8/21 15/90+16/21 15/90+8/42 45/90+8/21 15/90+24/21 15/90+8/63 75/90+8/21 15/90+40/21 15/90+56/21