Rational numbers are numbers that can be absolutely determined. This includes integers, limited decimals, repeating decimals, and fractions. Examples include 1, 1.25, 1.38383838..., and 1/2. Irrational numbers are numbers that cannot have their absolute value determined. This excludes every example for rational numbers. An example of an irrational number is 3.1415926535879... (pi) or 1.41421356237... (sqrt2)