math help

What is 9/10 + 4/8?

What is 9/10 + 4/8?

This is how we add

9
10
+
4
8

Step 1

Can you add yet? Nope! The denominators don't match. We need a common denominator. So next we take both denominators and multiply them. Next, take each numerator and multiply it by the denominator of the other term.

So, we multiply 9 by 8, and get 72, then we multiply 10 by 8 and get 80.

9/10 times 8

Now for the second term. You multiply 4 by 10, and get 40, then multiply 10 by 8 and get 80.

4/8 times 10

We now have a new problem, that looks like this:

72
80
+
40
80

Step 2

Since our denominators match, we can add the numerators.

72 + 40 = 112

That gives us the sum, which is

112
80

Step 3

Now, do we need to simplify this fraction?

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

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

112
80
÷ 2 =
56
40

Now, try the same number again.

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

56
40
÷ 2 =
28
20

Now, try the same number again.

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

28
20
÷ 2 =
14
10

Now, try the same number again.

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

14
10
÷ 2 =
7
5

Now, try the same number again.

Nope. Try the next prime number, 3...

Nope. Try the next prime number, 5...

Nope. Try the next prime number, 7...

No good. 7 is larger than 5. So we're done reducing.

Congratulations! Here's your final answer to 9/10 + 4/8

9
10
+
4
8
=
7
5
© 2014 Randy Tayler