math help

What is 21/33 + 8/10?

What is 21/33 + 8/10?

This is how you add

21
33
+
8
10

Step 1

We can't add two fractions with different denominators (the bottom number). So you need to get a common denominator - both bottom numbers need to match. To do this, you'll multiply the denominators times each other... but the numerators have to change, too. They get multiplied by the other term's denominator.

So we multiply 21 by 10, and get 210, then we multiply 33 by 10 and get 330.

21/33 times 10

Do the same for the second term. We multiply 8 by 33, and get 264, then multiply 33 by 10 and get 330.

8/10 times 33

So now our fractions look like this:

210
330
+
264
330

Step 2

Since our denominators match, we can add the numerators.

210 + 264 = 474

So the answer is:

474
330

Step 3

Last of all, we need to simplify the fraction, if possible. Can it be reduced to a simpler fraction?

To find out, we try dividing it by 2...

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

474
330
÷ 2 =
237
165

Let's try dividing by that again...

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:

237
165
÷ 3 =
79
55

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...

No good. 59 is larger than 55. So we're done reducing.

There you have it! Here's the final answer to 21/33 + 8/10

21
33
+
8
10
=
79
55
© 2014 Randy Tayler