WEBBasic Math & Pre-Algebra Cheat Sheet. Groups of Numbers. Natural or counting numbers: 1, 2, 3, 4,... Whole numbers: 0, 1, 2, 3,... Integers: ...-3, -2, -1, 0, 1, 2, 3, Rational numbers: Integers and fractions. Irrational numbers: Cannot be written as fractions: or π.