What is 21/63 + 11/12?

This is how you add

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 21 by 12, and get 252, then we multiply 63 by 12 and get 756.

Now for the second term. You multiply 11 by 63, and get 693, then multiply 63 by 12 and get 756.

We now have a new problem, that looks like this:

Step 2

Since our denominators match, we can add the numerators.

252 + 693 = 945

Answer:

Step 3

Now, do we need to simplify this fraction?

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

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

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

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

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

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

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

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 5...

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

Are both the numerator and the denominator evenly divisible by 7? Yes! So we reduce it:

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

No good. 7 is larger than 5. So we're done reducing.

And we're done! Here's the final answer to 21/63 + 11/12