It is two distinct concepts, both important. The one concept is the use of a positional or "place-value" notation for numbers. Place-value notation means you u

It is two distinct concepts, both important. The one concept is the use of a positional or "place-value" notation for numbers. Place-value notation means you use a base set of symbols, and then the position when using multiple digits is a multiplier. Compared to say Roman numerals this have the advantage that you can write arbitrarily large numbers. (The Romans didn't have a symbol for numbers larger than 1000, hence larger numbers became cumbersome to write.) More important though, arithmetic is much simpler using a place-value notion, because you can place numbers vertically and then perform the operation on one row at a time. Place-value notation requires a symbol for "nothing at this place", the "0". The post is about the oldest known use of "0" in a place-value system. (Which probably means the oldest use of a place-value system per se, since you cannot have a place-value system without "0".) However, using a place-value notation like decimal notation does not mean that you have to accept zero as a natural number. That is a separate issue.