math help

What is 72/63 + 3/8?

What is 72/63 + 3/8?

This is how to add

72
63
+
3
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 3 by 63, and get 189, then multiply 63 by 8 and get 504.

3/8 times 63

The problem now has new fractions to add:

576
504
+
189
504

Step 2

Since our denominators match, we can add the numerators.

576 + 189 = 765

This yields the answer

765
504

Step 3

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

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

No good. So next you try the next prime number, which is 3...

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

765
504
÷ 3 =
255
168

So far so good... let's try to divide by that number again.

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

255
168
÷ 3 =
85
56

So far so good... let's try to divide by that number again.

No good. So next you try the next prime number, which is 5...

No good. So next you try the next prime number, which is 7...

No good. So next you try the next prime number, which is 11...

No good. So next you try the next prime number, which is 13...

No good. So next you try the next prime number, which is 17...

No good. So next you try the next prime number, which is 19...

No good. So next you try the next prime number, which is 23...

No good. So next you try the next prime number, which is 29...

No good. So next you try the next prime number, which is 31...

No good. So next you try the next prime number, which is 37...

No good. So next you try the next prime number, which is 41...

No good. So next you try the next prime number, which is 43...

No good. So next you try the next prime number, which is 47...

No good. So next you try the next prime number, which is 53...

No good. So next you try the next prime number, which is 59...

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

And we're done! Here's the final answer to 72/63 + 3/8

72
63
+
3
8
=
85
56
© 2014 Randy Tayler