 What is 1/11 + 3/12? This is how to add

 1 11
+
 3 12

Step 1

Can you add yet? Nope! The denominators don't match. We need a common denominator. So next we take both denominators and multiply them. Next, take each numerator and multiply it by the denominator of the other term.

So, we multiply 1 by 12, and get 12, then we multiply 11 by 12 and get 132. Now for the second term. You multiply 3 by 11, and get 33, then multiply 11 by 12 and get 132. We now have a new problem, that looks like this:

 12 132
+
 33 132

Step 2

Since our denominators match, we can add the numerators.

12 + 33 = 45

 45 132

Step 3

Now, do we need to simplify this fraction?

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

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

Are both the numerator and the denominator evenly divisible by 3? Yes! So we reduce it:

 45 132
÷ 3 =
 15 44

Let's try dividing by that again...

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 15. So we're done reducing.

There you have it! Here's the final answer to 1/11 + 3/12

 1 11
+
 3 12
=
 15 44
© 2014 Randy Tayler