math help

What is 3/18 + 7/8?

What is 3/18 + 7/8?

Let's add

3
18
+
7
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 3 by 8, and get 24, then we multiply 18 by 8 and get 144.

3/18 times 8

Do the same for the second term. We multiply 7 by 18, and get 126, then multiply 18 by 8 and get 144.

7/8 times 18

So now our fractions look like this:

24
144
+
126
144

Step 2

Since our denominators match, we can add the numerators.

24 + 126 = 150

Now we have an answer.

150
144

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:

150
144
÷ 2 =
75
72

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:

75
72
÷ 3 =
25
24

Let's try dividing by that again...

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

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...

Nope! So now we try the next greatest prime number, 17...

Nope! So now we try the next greatest prime number, 19...

Nope! So now we try the next greatest prime number, 23...

Nope! So now we try the next greatest prime number, 29...

No good. 29 is larger than 25. So we're done reducing.

There you have it! Here's the final answer to 3/18 + 7/8

3
18
+
7
8
=
25
24
© 2014 Randy Tayler