math help

What is 21/33 + 7/8?

What is 21/33 + 7/8?

This is how to add

21
33
+
7
8

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 21 by 8, and get 168, then we multiply 33 by 8 and get 264.

21/33 times 8

Now for the second term. You multiply 7 by 33, and get 231, then multiply 33 by 8 and get 264.

7/8 times 33

This gives us a new problem that looks like so:

168
264
+
231
264

Step 2

Since our denominators match, we can add the numerators.

168 + 231 = 399

So what's the answer so far?

399
264

Step 3

Can this fraction be reduced?

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

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

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

399
264
÷ 3 =
133
88

Let's try dividing by that again...

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...

Nope! So now we try the next greatest prime number, 43...

Nope! So now we try the next greatest prime number, 47...

Nope! So now we try the next greatest prime number, 53...

Nope! So now we try the next greatest prime number, 59...

Nope! So now we try the next greatest prime number, 61...

Nope! So now we try the next greatest prime number, 67...

Nope! So now we try the next greatest prime number, 71...

Nope! So now we try the next greatest prime number, 73...

Nope! So now we try the next greatest prime number, 79...

Nope! So now we try the next greatest prime number, 83...

Nope! So now we try the next greatest prime number, 89...

No good. 89 is larger than 88. So we're done reducing.

There you have it! Here's the final answer to 21/33 + 7/8

21
33
+
7
8
=
133
88
© 2014 Randy Tayler