Numeric system without "zero", how to explain importance of zero to average person? As we all knew that Aryabhata (http://en.wikipedia.org/wiki/Aryabhata#Place_value_system_and_zero) invented zero ($0$) in our number system. I have few questions about it.


*

*How did the numeric system work before the invention of "zero" ?

*What difference does it make now ? Does it mean we can't we have series like (1-9,11-19,21-29 and so on....)

*How is the invention of computers and digital devices related to invention of zero ?


I want to answer this question to an average person, how would I proceed ?

I would start with roman numerals. This is something "average" person probably knows somewhat, so he has some ground to stand. I would explain that roman numeral system is additive: fifteen in roman numerals is XV i.e. X+V.
Then it should be explained that our common decimal system is in some sense additive as well, 15 is 10 + 5. It shows, how 0 is just a placeholder, something we can easily use to create 50 or 500 using just the same 5. With roman numerals we need separate symbols for V,L and D.
When goal is computers next step should be numeral systems with different base, mainly binary. 
