math help

What is 15/60 + 9/11?

What is 15/60 + 9/11?

Here's how we add

15
60
+
9
11

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 15 by 11, and get 165, then we multiply 60 by 11 and get 660.

15/60 times 11

Now for the second term. You multiply 9 by 60, and get 540, then multiply 60 by 11 and get 660.

9/11 times 60

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

165
660
+
540
660

Step 2

Since our denominators match, we can add the numerators.

165 + 540 = 705

That gives us the sum, which is

705
660

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:

705
660
÷ 3 =
235
220

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...

Are both the numerator and the denominator evenly divisible by 5? Yes! So we reduce it:

235
220
÷ 5 =
47
44

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 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. So next you try the next prime number, which is 29...

No good. So next you try the next prime number, which is 31...

No good. So next you try the next prime number, which is 37...

No good. So next you try the next prime number, which is 41...

No good. So next you try the next prime number, which is 43...

No good. So next you try the next prime number, which is 47...

No good. 47 is larger than 44. So we're done reducing.

And we're done! Here's the final answer to 15/60 + 9/11

15
60
+
9
11
=
47
44
© 2014 Randy Tayler