Examples

• The relation that associates a whole number with twice its value is a numerical function. It can be defined as follows: [latex]f : \mathbb{N} → \mathbb{N}\space | \space f(x) = 2x[/latex]. 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.