math help

What is 5/100 + 4/8?

What is 5/100 + 4/8?

Here's how you add

5
100
+
4
8

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 5 by 8, and get 40, then we multiply 100 by 8 and get 800.

5/100 times 8

Now for the second term. You multiply 4 by 100, and get 400, then multiply 100 by 8 and get 800.

4/8 times 100

This gives us a new problem that looks like so:

40
800
+
400
800

Step 2

Since our denominators match, we can add the numerators.

40 + 400 = 440

So what's the answer so far?

440
800

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:

440
800
÷ 2 =
220
400

Let's try dividing by that again...

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

220
400
÷ 2 =
110
200

Let's try dividing by that again...

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

110
200
÷ 2 =
55
100

Let's try dividing by that again...

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

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:

55
100
÷ 5 =
11
20

Let's try dividing by that again...

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...

No good. 13 is larger than 11. So we're done reducing.

There you have it! Here's the final answer to 5/100 + 4/8

5
100
+
4
8
=
11
20
© 2014 Randy Tayler