math help

What is 21/11 + 4/7?

What is 21/11 + 4/7?

Let's add

21
11
+
4
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 11 by 7 and get 77.

21/11 times 7

Now for the second term. You multiply 4 by 11, and get 44, then multiply 11 by 7 and get 77.

4/7 times 11

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

147
77
+
44
77

Step 2

Since our denominators match, we can add the numerators.

147 + 44 = 191

Answer:

191
77

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...

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 21/11 + 4/7

21
11
+
4
7
=
191
77
© 2014 Randy Tayler