math help

What is 72/63 + 8/12?

What is 72/63 + 8/12?

Let's add

72
63
+
8
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 72 by 12, and get 864, then we multiply 63 by 12 and get 756.

72/63 times 12

Now for the second term. You multiply 8 by 63, and get 504, then multiply 63 by 12 and get 756.

8/12 times 63

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

864
756
+
504
756

Step 2

Since our denominators match, we can add the numerators.

864 + 504 = 1368

Answer:

1368
756

Step 3

Now, do we need to simplify this fraction?

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

Are both the numerator and the denominator evenly divisible by 2? Yes! So we reduce it:

1368
756
÷ 2 =
684
378

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

Are both the numerator and the denominator evenly divisible by 2? Yes! So we reduce it:

684
378
÷ 2 =
342
189

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...

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

342
189
÷ 3 =
114
63

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:

114
63
÷ 3 =
38
21

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...

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. So next you try the next prime number, which is 23...

No good. 23 is larger than 21. So we're done reducing.

And we're done! Here's the final answer to 72/63 + 8/12

72
63
+
8
12
=
38
21
© 2014 Randy Tayler