zero is a number which means an amount of null size; that is, if the number of brothers is zero, that means the same thing as having no brothers, and if something has a weight of zero, it has no weight. if the difference between the numbers of pieces in two piles is zero, it means the two piles have an equal number of pieces. before counting starts, the result can be assumed to be zero; that is the number of items counted before one counts the first item, and counting the first item brings the result to one. and if there are no items to be counted, zero remains the final result.