math help

What is 28/100 + 4/8?

What is 28/100 + 4/8?

Here's how to add

28
100
+
4
8

Step 1

We can't add two fractions with different denominators (the bottom number). So you need to get a common denominator - both bottom numbers need to match. To do this, you'll multiply the denominators times each other... but the numerators have to change, too. They get multiplied by the other term's denominator.

So we multiply 28 by 8, and get 224, then we multiply 100 by 8 and get 800.

28/100 times 8

Do the same for the second term. We multiply 4 by 100, and get 400, then multiply 100 by 8 and get 800.

4/8 times 100

So now our fractions look like this:

224
800
+
400
800

Step 2

Since our denominators match, we can add the numerators.

224 + 400 = 624

Now we have an answer.

624
800

Step 3

Last of all, we need to simplify the fraction, if possible. Can it be reduced to a simpler fraction?

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:

624
800
÷ 2 =
312
400

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:

312
400
÷ 2 =
156
200

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:

156
200
÷ 2 =
78
100

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:

78
100
÷ 2 =
39
50

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. 41 is larger than 39. So we're done reducing.

And we're done! Here's the final answer to 28/100 + 4/8

28
100
+
4
8
=
39
50
© 2014 Randy Tayler