What is nine plus nine? i mean what does it equal?

It equals 18.

Step-by-step explanation:

Nine is worth 9 1's.

Nine is also worth 9 1's.

So if you count up all the 1's, it will equal 18.

step-by-step explanation:

you can add the two numbers and divide the result by 2. or you can find the gap between the two numbers and add half of this to the smaller number.