math help

What is 21/11 + 2/10?

What is 21/11 + 2/10?

This is how you add

21
11
+
2
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 11 by 10 and get 110.

21/11 times 10

Do the same for the second term. We multiply 2 by 11, and get 22, then multiply 11 by 10 and get 110.

2/10 times 11

So now our fractions look like this:

210
110
+
22
110

Step 2

Since our denominators match, we can add the numerators.

210 + 22 = 232

Now we have an answer.

232
110

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:

232
110
÷ 2 =
116
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 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. 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 55. So we're done reducing.

And we're done! Here's the final answer to 21/11 + 2/10

21
11
+
2
10
=
116
55
© 2014 Randy Tayler