Whats 9 + 10

it is 21

9 plus 10 equals 19, and not 18 or 21.

Please use a calculator to check your answers.

I hope this helps! :)

To find the answer to the expression 9 + 10, you simply need to add the two numbers together. In this case, 9 plus 10 equals 19.

Base11, it is 18