The multiplication of natural numbers is defined by repeated addition, so 3 × 2 = 2 + 2 + 2 = 6. Multiplication of (potentially negative) integers can then be determined as with −3 × 2 = −(3 × 2) = −6. And this may be extended to multiplication of fractions, and every rational number may be expressed as a fraction. Finally, real numbers can be considered as limits of rational sequences and their product taken to be the limit of the products of those sequences. See algebra of limits.