math help

What is 21/33 + 4/10?

What is 21/33 + 4/10?

Here's how you add

21
33
+
4
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 4 by 33, and get 132, then multiply 33 by 10 and get 330.

4/10 times 33

So now our fractions look like this:

210
330
+
132
330

Step 2

Since our denominators match, we can add the numerators.

210 + 132 = 342

Now we have an answer.

342
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:

342
330
÷ 2 =
171
165

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...

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

171
165
÷ 3 =
57
55

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...

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. So next you try the next prime number, which is 53...

No good. So next you try the next prime number, which is 59...

No good. 59 is larger than 57. So we're done reducing.

And we're done! Here's the final answer to 21/33 + 4/10

21
33
+
4
10
=
57
55
© 2014 Randy Tayler