 # What is 2/12 + 9/10? Here's how you add

 2 12
+
 9 10

## Step 1

We still have different denominators (bottom numbers), though, so we need to get a common denominator. This will make the bottom numbers match. Multiply the denominators together first. Now, multiply each numerator by the other term's denominator.

Now we multiply 2 by 10, and get 20, then we multiply 12 by 10 and get 120. Now for the second term. You multiply 9 by 12, and get 108, then multiply 12 by 10 and get 120. This gives us a new problem that looks like so:

 20 120
+
 108 120

## Step 2

Since our denominators match, we can add the numerators.

20 + 108 = 128

That gives us an answer of

 128 120

## Step 3

Can this fraction be reduced?

First, we attempt to divide it by 2...

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

 128 120
÷ 2 =
 64 60

Let's try dividing by that again...

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

 64 60
÷ 2 =
 32 30

Let's try dividing by that again...

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

 32 30
÷ 2 =
 16 15

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...

No good. 17 is larger than 16. So we're done reducing.

There you have it! Here's the final answer to 2/12 + 9/10

 2 12
+
 9 10
=
 16 15
© 2014 Randy Tayler