math help

What is 4/40 + 8/12?

What is 4/40 + 8/12?

Let's add

4
40
+
8
12

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 4 by 12, and get 48, then we multiply 40 by 12 and get 480.

4/40 times 12

Do the same for the second term. We multiply 8 by 40, and get 320, then multiply 40 by 12 and get 480.

8/12 times 40

So now our fractions look like this:

48
480
+
320
480

Step 2

Since our denominators match, we can add the numerators.

48 + 320 = 368

So the answer is:

368
480

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:

368
480
÷ 2 =
184
240

Now, try the same number again.

Are both the numerator and the denominator evenly divisible by 2? Yes! So we reduce it:

184
240
÷ 2 =
92
120

Now, try the same number again.

Are both the numerator and the denominator evenly divisible by 2? Yes! So we reduce it:

92
120
÷ 2 =
46
60

Now, try the same number again.

Are both the numerator and the denominator evenly divisible by 2? Yes! So we reduce it:

46
60
÷ 2 =
23
30

Now, try the same number again.

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...

No good. 29 is larger than 23. So we're done reducing.

Congratulations! Here's your final answer to 4/40 + 8/12

4
40
+
8
12
=
23
30
© 2014 Randy Tayler