math help

What is 20/64 + 5/12?

What is 20/64 + 5/12?

This is how we add

20
64
+
5
12

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 20 by 12, and get 240, then we multiply 64 by 12 and get 768.

20/64 times 12

Now for the second term. You multiply 5 by 64, and get 320, then multiply 64 by 12 and get 768.

5/12 times 64

This gives us a new problem that looks like so:

240
768
+
320
768

Step 2

Since our denominators match, we can add the numerators.

240 + 320 = 560

So what's the answer so far?

560
768

Step 3

Can this fraction be reduced?

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

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

560
768
÷ 2 =
280
384

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:

280
384
÷ 2 =
140
192

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:

140
192
÷ 2 =
70
96

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:

70
96
÷ 2 =
35
48

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...

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. 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. 37 is larger than 35. So we're done reducing.

And we're done! Here's the final answer to 20/64 + 5/12

20
64
+
5
12
=
35
48
© 2014 Randy Tayler