math help

What is 72/63 + 5/8?

What is 72/63 + 5/8?

Let's add

72
63
+
5
8

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 72 by 8, and get 576, then we multiply 63 by 8 and get 504.

72/63 times 8

Do the same for the second term. We multiply 5 by 63, and get 315, then multiply 63 by 8 and get 504.

5/8 times 63

So now our fractions look like this:

576
504
+
315
504

Step 2

Since our denominators match, we can add the numerators.

576 + 315 = 891

Now we have an answer.

891
504

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...

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

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

891
504
÷ 3 =
297
168

Now, try the same number again.

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

297
168
÷ 3 =
99
56

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...

No good. 59 is larger than 56. So we're done reducing.

Congratulations! Here's your final answer to 72/63 + 5/8

72
63
+
5
8
=
99
56
© 2014 Randy Tayler