the "number" zero (as in the "zero brothers" example above) is not the same as the "numeral" or "digit" zero, used in numeral systems using positional notation. successive positions of digits have higher values, so the digit zero is used to skip a position and give appropriate value to the preceding and following digits. a zero digit is not always necessary in a different positional number system. something called bijective numeration is a possible example of a system without zeroes.