math help

What is 21/33 + 6/7?

What is 21/33 + 6/7?

Here's how we add

21
33
+
6
7

Step 1

Can you add yet? Nope! The denominators don't match. We need a common denominator. So next we take both denominators and multiply them. Next, take each numerator and multiply it by the denominator of the other term.

So, we multiply 21 by 7, and get 147, then we multiply 33 by 7 and get 231.

21/33 times 7

Now for the second term. You multiply 6 by 33, and get 198, then multiply 33 by 7 and get 231.

6/7 times 33

We now have a new problem, that looks like this:

147
231
+
198
231

Step 2

Since our denominators match, we can add the numerators.

147 + 198 = 345

Answer:

345
231

Step 3

Now, do we need to simplify this fraction?

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

Nope. Try the next prime number, 3...

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

345
231
÷ 3 =
115
77

Now, try the same number again.

Nope. Try the next prime number, 5...

Nope. Try the next prime number, 7...

Nope. Try the next prime number, 11...

Nope. Try the next prime number, 13...

Nope. Try the next prime number, 17...

Nope. Try the next prime number, 19...

Nope. Try the next prime number, 23...

Nope. Try the next prime number, 29...

Nope. Try the next prime number, 31...

Nope. Try the next prime number, 37...

Nope. Try the next prime number, 41...

Nope. Try the next prime number, 43...

Nope. Try the next prime number, 47...

Nope. Try the next prime number, 53...

Nope. Try the next prime number, 59...

Nope. Try the next prime number, 61...

Nope. Try the next prime number, 67...

Nope. Try the next prime number, 71...

Nope. Try the next prime number, 73...

Nope. Try the next prime number, 79...

No good. 79 is larger than 77. So we're done reducing.

Congratulations! Here's your final answer to 21/33 + 6/7

21
33
+
6
7
=
115
77
© 2014 Randy Tayler