Function that takes on values in a set of numbers.

A numerical function does not necessarily have a set of numbers as a domain, as is the case in probability; however, its image is always a set of numbers.

### Examples

- The relation that associates a whole number with twice its value is a numerical function.

It can be defined as follows: \(f : \mathbb{N} → \mathbb{N}\space | \space f(x) = 2x\).

The domain of this function is W and its image is the set of even numbers. - If the cards in a standard deck of 52 playing cards are given a specific value, such that:
- the value of all the cards except for the face cards is written on the cards (2 to 10),
- the face cards have a value of 11,
- the aces have a value of 12,

then this distribution of points is a numerical function in which the elements of the domain are not numbers.