math help

What is 21/33 + 7/12?

What is 21/33 + 7/12?

This is how we add

21
33
+
7
12

Step 1

We still have different denominators (bottom numbers), though, so we need to get a common denominator. This will make the bottom numbers match. Multiply the denominators together first. Now, multiply each numerator by the other term's denominator.

Now we multiply 21 by 12, and get 252, then we multiply 33 by 12 and get 396.

21/33 times 12

Now for the second term. You multiply 7 by 33, and get 231, then multiply 33 by 12 and get 396.

7/12 times 33

This gives us a new problem that looks like so:

252
396
+
231
396

Step 2

Since our denominators match, we can add the numerators.

252 + 231 = 483

That gives us an answer of

483
396

Step 3

Can this fraction be reduced?

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:

483
396
÷ 3 =
161
132

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...

Nope. Try the next prime number, 83...

Nope. Try the next prime number, 89...

Nope. Try the next prime number, 97...

Nope. Try the next prime number, 101...

Nope. Try the next prime number, 103...

Nope. Try the next prime number, 107...

Nope. Try the next prime number, 109...

Nope. Try the next prime number, 113...

Nope. Try the next prime number, 127...

Nope. Try the next prime number, 131...

Nope. Try the next prime number, 137...

No good. 137 is larger than 132. So we're done reducing.

Congratulations! Here's your final answer to 21/33 + 7/12

21
33
+
7
12
=
161
132
© 2014 Randy Tayler