Subtract 1/42 from 21/40
21/40 - 1/42 is 421/840.
Steps for subtracting fractions
- Find the least common denominator or LCM of the two denominators:
LCM of 40 and 42 is 840
Next, find the equivalent fraction of both fractional numbers with denominator 840 - For the 1st fraction, since 40 × 21 = 840,
21/40 = 21 × 21/40 × 21 = 441/840 - Likewise, for the 2nd fraction, since 42 × 20 = 840,
1/42 = 1 × 20/42 × 20 = 20/840 - Subtract the two like fractions:
441/840 - 20/840 = 441 - 20/840 = 421/840
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