math help

What is 80/2 + 1/9?

What is 80/2 + 1/9?

Let's add

80
2
+
1
9

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 80 by 9, and get 720, then we multiply 2 by 9 and get 18.

80/2 times 9

Do the same for the second term. We multiply 1 by 2, and get 2, then multiply 2 by 9 and get 18.

1/9 times 2

So now our fractions look like this:

720
18
+
2
18

Step 2

Since our denominators match, we can add the numerators.

720 + 2 = 722

Now we have an answer.

722
18

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:

722
18
÷ 2 =
361
9

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. 11 is larger than 9. So we're done reducing.

And we're done! Here's the final answer to 80/2 + 1/9

80
2
+
1
9
=
361
9
© 2014 Randy Tayler