Arithmetic/Types of Numbers/Integer Number

An integer number is any of: a positive whole number (a positive integer), a negative whole number (a negative integer), or zero. Positive Integer A Positive Integer is a natural number greater than 0, i.e. a whole number. A Positive Integer can be expressed mathematically: I > 0 = {+1,+2,+3,+4,+5,+6,+7,+8,+9,...} Positive numbers are often written without a + sign: I > 0 = {1,2,3,4,5,6,7,8,9,...} Negative Integer A Negative Integer is a negative whole number. This is represented by a - sign on the left side of the value. I < 0 = {-1,-2,-3,-4,-5,-6,-7,-8,-9,...} Number Zero The Integers include a new number, 0. Rules a + 0 = a a - 0 = a a × 0 = 0 a / 0 is not defined. a + a = 2a a - a = 0 a × a = a2 a / a = 1 (except for a = 0, which is not defined, see rule 4) a - (-a) = 2a a × (-a) = - a2 a / (-a) = -1 (except for a = 0, which is not defined, see rule 4)