math help

What is 15/60 + 8/11?

What is 15/60 + 8/11?

This is how we add

15
60
+
8
11

Step 1

Of course, you can't add two fractions if the denominators (bottom numbers) don't match. To get a common denominator, multiply the denominators together. Then we fix the numerators by multiplying each one by their other term's denominator.

Now you multiply 15 by 11, and get 165, then we multiply 60 by 11 and get 660.

15/60 times 11

Do the same for the second term. We multiply 8 by 60, and get 480, then multiply 60 by 11 and get 660.

8/11 times 60

The problem now has new fractions to add:

165
660
+
480
660

Step 2

Since our denominators match, we can add the numerators.

165 + 480 = 645

The sum we get is

645
660

Step 3

The last step is to reduce the fraction if we can.

To find out, we try dividing 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:

645
660
÷ 3 =
215
220

Now, try the same number again.

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

Are both the numerator and the denominator evenly divisible by 5? Yes! So we reduce it:

215
220
÷ 5 =
43
44

Now, try the same number again.

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...

No good. 47 is larger than 43. So we're done reducing.

Congratulations! Here's your final answer to 15/60 + 8/11

15
60
+
8
11
=
43
44
© 2014 Randy Tayler