math help

What is 100/100 + 9/12?

What is 100/100 + 9/12?

Here's how we add

100
100
+
9
12

Step 1

We still have different denominators (bottom numbers), though, so we need to get a common denominator. This will make the bottom numbers match. Multiply the denominators together first. Now, multiply each numerator by the other term's denominator.

Now we multiply 100 by 12, and get 1200, then we multiply 100 by 12 and get 1200.

100/100 times 12

Now for the second term. You multiply 9 by 100, and get 900, then multiply 100 by 12 and get 1200.

9/12 times 100

This gives us a new problem that looks like so:

1200
1200
+
900
1200

Step 2

Since our denominators match, we can add the numerators.

1200 + 900 = 2100

So what's the answer so far?

2100
1200

Step 3

Can this fraction be reduced?

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

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

2100
1200
÷ 2 =
1050
600

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:

1050
600
÷ 2 =
525
300

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...

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

525
300
÷ 3 =
175
100

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...

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

175
100
÷ 5 =
35
20

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

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

35
20
÷ 5 =
7
4

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

No good. 5 is larger than 4. So we're done reducing.

And we're done! Here's the final answer to 100/100 + 9/12

100
100
+
9
12
=
7
4
© 2014 Randy Tayler