Why was a zero symbol necessary in a positional number system?

In a positional number system, the value of a digit is determined by its position, which corresponds to a specific power of the base. A zero symbol is necessary to act as a placeholder for any power of the base that is not actually present in a given number.12

Without this placeholder, it would be impossible to distinguish between numbers of different magnitudes. For example, without a zero, the sequence "792" could be ambiguous, potentially representing 792, 7,092, or 70,092 depending on the intended place values. By using a symbol to mark a "vacant" position, the system ensures that the remaining digits maintain their correct place value, allowing for the clear representation of any number.12

While earlier civilizations like the Babylonians used various symbols to mark empty positions, the Hindus were the first to develop the modern use of zero as a distinct numeral. They referred to this concept as sunya, meaning "vacant," which provided the essential clarity required for complex arithmetic and calculation.12