What is 9/10 + 4/5?

Here's how to add

Step 1

Our denominators (bottom numbers) don't match, so we can't add yet.

Since 5 is evenly divided by 10, we can multiply just one term to get a common denominator.

Multiply 4 by 2, and get 8, then we multiply 5 by 2 and get 10.

So now our fractions look like this:

Step 2

Since our denominators match, we can add the numerators.

9 + 8 = 17

Now we have an answer.

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...

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

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

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

Nope. Try the next prime number, 11...

No good. 11 is larger than 10. So we're done reducing.

Congratulations! Here's your final answer to 9/10 + 4/5