What is 21/63 + 2/5?

Here's how to 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 5, and get 105, then we multiply 63 by 5 and get 315.

Now for the second term. You multiply 2 by 63, and get 126, then multiply 63 by 5 and get 315.

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

Step 2

Since our denominators match, we can add the numerators.

105 + 126 = 231

Answer:

Step 3

Now, do we need to simplify this fraction?

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

Nope. Try the next prime number, 3...

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

Now, try the same number again.

Nope. Try the next prime number, 5...

Nope. Try the next prime number, 7...

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

Now, try the same number again.

Nope. Try the next prime number, 11...

Nope. Try the next prime number, 13...

No good. 13 is larger than 11. So we're done reducing.

Congratulations! Here's your final answer to 21/63 + 2/5