math help

What is 72/63 + 7/8?

What is 72/63 + 7/8?

This is how we add

72
63
+
7
8

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 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 7 by 63, and get 441, then multiply 63 by 8 and get 504.

7/8 times 63

The problem now has new fractions to add:

576
504
+
441
504

Step 2

Since our denominators match, we can add the numerators.

576 + 441 = 1017

The sum we get is

1017
504

Step 3

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

To find out, we try dividing it by 2...

Nope! So now we try the next greatest prime number, 3...

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

1017
504
÷ 3 =
339
168

Let's try dividing by that again...

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

339
168
÷ 3 =
113
56

Let's try dividing by that again...

Nope! So now we try the next greatest prime number, 5...

Nope! So now we try the next greatest prime number, 7...

Nope! So now we try the next greatest prime number, 11...

Nope! So now we try the next greatest prime number, 13...

Nope! So now we try the next greatest prime number, 17...

Nope! So now we try the next greatest prime number, 19...

Nope! So now we try the next greatest prime number, 23...

Nope! So now we try the next greatest prime number, 29...

Nope! So now we try the next greatest prime number, 31...

Nope! So now we try the next greatest prime number, 37...

Nope! So now we try the next greatest prime number, 41...

Nope! So now we try the next greatest prime number, 43...

Nope! So now we try the next greatest prime number, 47...

Nope! So now we try the next greatest prime number, 53...

Nope! So now we try the next greatest prime number, 59...

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

There you have it! Here's the final answer to 72/63 + 7/8

72
63
+
7
8
=
113
56
© 2014 Randy Tayler