Add 21/14 and 9/40, Solve 1 7/14 + 9/40 as a fraction

Add 21/14 and 9/40

1^st number: 1 7/14, 2^nd number: 9/40

21/14 + 9/40 is 69/40.

Find the least common denominator or LCM of the two denominators:
LCM of 14 and 40 is 280

Next, find the equivalent fraction of both fractional numbers with denominator 280
For the 1st fraction, since 14 × 20 = 280,
21/14 = 21 × 20/14 × 20 = 420/280
Likewise, for the 2nd fraction, since 40 × 7 = 280,
9/40 = 9 × 7/40 × 7 = 63/280
Add the two like fractions:
420/280 + 63/280 = 420 + 63/280 = 483/280
483/280 simplified gives 69/40
So, 21/14 + 9/40 = 69/40
In mixed form: 129/40

MathStep (Works offline)

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