What would change if we added another number to how we count?
For example, another number would go between nine and ten, then we'd have numbers like this
> 1 2 3 4 5 6 7 8 9 x 10
> 11 12 13 14 15 16 17 18 19 1x 20
Is there a reason we have as many digits as we do per ten?
The babylonians used 60 symbols/numbers (base 60)'
Computer use 2 symbols/numbers. (base 2) which is also called the binary number. I apologize for the elitist answers here but your qustion make it sound like you are 15 years old who has not finished school yet. I am just answering for the little hope i have that you are some old bastard who slept through elementary school.