Note 1 to entry: Division is defined for rational numbers and extended to other classes of numbers, except the division by zero, and to mathematical entities such as polynomials, and also to quantities and units.

Note 2 to entry: In a division $a/b$, the first element a is called "dividend" and the second is called "divisor".

Note 3 to entry: The division of entities a and b is expressed by the words "a divided by b" or "a by b" and denoted by $\frac{a}{b}$, $a/b$ or $a{b}^{-1}$.