What is 21/63 + 1/4?

Here's how you add

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 21 by 4, and get 84, then we multiply 63 by 4 and get 252.

Now for the second term. You multiply 1 by 63, and get 63, then multiply 63 by 4 and get 252.

This gives us a new problem that looks like so:

Step 2

Since our denominators match, we can add the numerators.

84 + 63 = 147

That gives us an answer of

Step 3

Can this fraction be reduced?

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.

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. So next you try the next prime number, which is 11...

No good. 11 is larger than 7. So we're done reducing.

And we're done! Here's the final answer to 21/63 + 1/4