 # What is 3/7 + 8/12? This is how you add

 3 7
+
 8 12

## Step 1

Of course, you can't add two fractions if the denominators (bottom numbers) don't match. To get a common denominator, multiply the denominators together. Then we fix the numerators by multiplying each one by their other term's denominator.

Now you multiply 3 by 12, and get 36, then we multiply 7 by 12 and get 84. Do the same for the second term. We multiply 8 by 7, and get 56, then multiply 7 by 12 and get 84. The problem now has new fractions to add:

 36 84
+
 56 84

## Step 2

Since our denominators match, we can add the numerators.

36 + 56 = 92

The sum we get is

 92 84

## Step 3

The last step is to reduce the fraction if we can.

To find out, we try dividing it by 2...

Are both the numerator and the denominator evenly divisible by 2? Yes! So we reduce it:

 92 84
÷ 2 =
 46 42

Let's try dividing by that again...

Are both the numerator and the denominator evenly divisible by 2? Yes! So we reduce it:

 46 42
÷ 2 =
 23 21

Let's try dividing by that again...

Nope! So now we try the next greatest prime number, 3...

Nope! So now we try the next greatest prime number, 5...

Nope! So now we try the next greatest prime number, 7...

Nope! So now we try the next greatest prime number, 11...

Nope! So now we try the next greatest prime number, 13...

Nope! So now we try the next greatest prime number, 17...

Nope! So now we try the next greatest prime number, 19...

Nope! So now we try the next greatest prime number, 23...

No good. 23 is larger than 21. So we're done reducing.

There you have it! Here's the final answer to 3/7 + 8/12

 3 7
+
 8 12
=
 23 21
© 2014 Randy Tayler