Add 9/45 and 84/21, Solve 9/45 + 4 0/21 as a fraction

Add 9/45 and 84/21

1^st number: 9/45, 2^nd number: 4 0/21

9/45 + 84/21 is 21/5.

Find the least common denominator or LCM of the two denominators:
LCM of 45 and 21 is 315

Next, find the equivalent fraction of both fractional numbers with denominator 315
For the 1st fraction, since 45 × 7 = 315,
9/45 = 9 × 7/45 × 7 = 63/315
Likewise, for the 2nd fraction, since 21 × 15 = 315,
84/21 = 84 × 15/21 × 15 = 1260/315
Add the two like fractions:
63/315 + 1260/315 = 63 + 1260/315 = 1323/315
1323/315 simplified gives 21/5
So, 9/45 + 84/21 = 21/5
In mixed form: 41/5

MathStep (Works offline)

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