Zero is a real number that comes before the number 1. It is most often defined as a whole number, natural number or a counting number.
Zero is neither a positive nor a negative number and doesn't follow the normal set of rules used in math. In multiplication and division, 0 multiplied or divided by any other number is always equal to 0. In addition, a number added to 0 results in the exact same number. In subtraction, 0 produces the same effect as with addition when 0 is subtracted from a number. If a number is subtracted from 0, the result is the negation of the number. Zero is used to also show the empty places in the ones, tens and hundreds places.