 What is 1/11 + 2/12? Here's how you add

 1 11
+
 2 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 1 by 12, and get 12, then we multiply 11 by 12 and get 132. Do the same for the second term. We multiply 2 by 11, and get 22, then multiply 11 by 12 and get 132. The problem now has new fractions to add:

 12 132
+
 22 132

Step 2

Since our denominators match, we can add the numerators.

12 + 22 = 34

This yields the answer

 34 132

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:

 34 132
÷ 2 =
 17 66

So far so good... let's try to divide by that number again.

No good. So next you try the next prime number, which is 3...

No good. So next you try the next prime number, which is 5...

No good. So next you try the next prime number, which is 7...

No good. So next you try the next prime number, which is 11...

No good. So next you try the next prime number, which is 13...

No good. So next you try the next prime number, which is 17...

No good. So next you try the next prime number, which is 19...

No good. 19 is larger than 17. So we're done reducing.

And we're done! Here's the final answer to 1/11 + 2/12

 1 11
+
 2 12
=
 17 66
© 2014 Randy Tayler