Subtract 21/42 from 1/18
1/18 - 21/42 is -4/9.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 18 and 42 is 126
Next, find the equivalent fraction of both fractional numbers with denominator 126 - For the 1st fraction, since 18 × 7 = 126,
1/18 = 1 × 7/18 × 7 = 7/126 - Likewise, for the 2nd fraction, since 42 × 3 = 126,
21/42 = 21 × 3/42 × 3 = 63/126 - Subtract the two like fractions:
7/126 - 63/126 = 7 - 63/126 = -56/126 - After reducing the fraction, the answer is -4/9
MathStep (Works offline)
Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad
Related: 2/18-21/42 1/36-21/42 1/18-21/84 3/18-21/42 1/18-63/42 1/54-21/42 5/18-21/42 1/90-21/42 7/18-21/42