math help

What is 100/72 + 9/10?

What is 100/72 + 9/10?

This is how you add

100
72
+
9
10

Step 1

Can you add yet? Nope! The denominators don't match. We need a common denominator. So next we take both denominators and multiply them. Next, take each numerator and multiply it by the denominator of the other term.

So, we multiply 100 by 10, and get 1000, then we multiply 72 by 10 and get 720.

100/72 times 10

Now for the second term. You multiply 9 by 72, and get 648, then multiply 72 by 10 and get 720.

9/10 times 72

We now have a new problem, that looks like this:

1000
720
+
648
720

Step 2

Since our denominators match, we can add the numerators.

1000 + 648 = 1648

That gives us the sum, which is

1648
720

Step 3

Now, do we need to simplify this fraction?

First, we attempt to divide it by 2...

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

1648
720
÷ 2 =
824
360

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

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

824
360
÷ 2 =
412
180

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

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

412
180
÷ 2 =
206
90

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

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

206
90
÷ 2 =
103
45

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 3...

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. 47 is larger than 45. So we're done reducing.

And we're done! Here's the final answer to 100/72 + 9/10

100
72
+
9
10
=
103
45
© 2014 Randy Tayler