Subtract 21/90 from 4/81
4/81 - 21/90 is -149/810.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 81 and 90 is 810
Next, find the equivalent fraction of both fractional numbers with denominator 810 - For the 1st fraction, since 81 × 10 = 810,
4/81 = 4 × 10/81 × 10 = 40/810 - Likewise, for the 2nd fraction, since 90 × 9 = 810,
21/90 = 21 × 9/90 × 9 = 189/810 - Subtract the two like fractions:
40/810 - 189/810 = 40 - 189/810 = -149/810
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