math help

What is 5/100 + 9/12?

What is 5/100 + 9/12?

Here's how to add

5
100
+
9
12

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 5 by 12, and get 60, then we multiply 100 by 12 and get 1200.

5/100 times 12

Do the same for the second term. We multiply 9 by 100, and get 900, then multiply 100 by 12 and get 1200.

9/12 times 100

The problem now has new fractions to add:

60
1200
+
900
1200

Step 2

Since our denominators match, we can add the numerators.

60 + 900 = 960

The sum we get is

960
1200

Step 3

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

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

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

960
1200
÷ 2 =
480
600

Let's try dividing by that again...

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

480
600
÷ 2 =
240
300

Let's try dividing by that again...

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

240
300
÷ 2 =
120
150

Let's try dividing by that again...

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

120
150
÷ 2 =
60
75

Let's try dividing by that again...

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:

60
75
÷ 3 =
20
25

Let's try dividing by that again...

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

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

20
25
÷ 5 =
4
5

Let's try dividing by that again...

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

There you have it! Here's the final answer to 5/100 + 9/12

5
100
+
9
12
=
4
5
© 2014 Randy Tayler