math help

What is 12/13 + 8/12?

What is 12/13 + 8/12?

This is how we add

12
13
+
8
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 12 by 12, and get 144, then we multiply 13 by 12 and get 156.

12/13 times 12

Now for the second term. You multiply 8 by 13, and get 104, then multiply 13 by 12 and get 156.

8/12 times 13

This gives us a new problem that looks like so:

144
156
+
104
156

Step 2

Since our denominators match, we can add the numerators.

144 + 104 = 248

So what's the answer so far?

248
156

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:

248
156
÷ 2 =
124
78

Let's try dividing by that again...

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

124
78
÷ 2 =
62
39

Let's try dividing by that again...

Nope! So now we try the next greatest prime number, 3...

Nope! So now we try the next greatest prime number, 5...

Nope! So now we try the next greatest prime number, 7...

Nope! So now we try the next greatest prime number, 11...

Nope! So now we try the next greatest prime number, 13...

Nope! So now we try the next greatest prime number, 17...

Nope! So now we try the next greatest prime number, 19...

Nope! So now we try the next greatest prime number, 23...

Nope! So now we try the next greatest prime number, 29...

Nope! So now we try the next greatest prime number, 31...

Nope! So now we try the next greatest prime number, 37...

Nope! So now we try the next greatest prime number, 41...

No good. 41 is larger than 39. So we're done reducing.

There you have it! Here's the final answer to 12/13 + 8/12

12
13
+
8
12
=
62
39
© 2014 Randy Tayler