Subtract 21/81 from 21/16, Solve 1 5/16

Subtract 21/81 from 21/16

1^st number: 1 5/16, 2^nd number: 21/81

21/16 - 21/81 is 455/432.

Find the least common denominator or LCM of the two denominators:
LCM of 16 and 81 is 1296

Next, find the equivalent fraction of both fractional numbers with denominator 1296
For the 1st fraction, since 16 × 81 = 1296,
21/16 = 21 × 81/16 × 81 = 1701/1296
Likewise, for the 2nd fraction, since 81 × 16 = 1296,
21/81 = 21 × 16/81 × 16 = 336/1296
Subtract the two like fractions:
1701/1296 - 336/1296 = 1701 - 336/1296 = 1365/1296
After reducing the fraction, the answer is 455/432
In mixed form: 123/432

MathStep (Works offline)

Download our mobile app and learn to work with fractions in your own time:
Android and iPhone/ iPad