# Norm (mathematics) facts for kids

In mathematics, the **norm** of a vector is its length. A **vector** is a mathematical object that has a size, called the *magnitude*, and a direction. For the real numbers, the only norm is the absolute value. For spaces with more dimensions, the norm can be any function with the following three properties:

- Scales for real numbers , that is, .
- Function of sum is less than sum of functions, that is, (also known as the triangle inequality).
- if and only if .

## Definition

For a vector , the associated norm is written as , or L where is some value. The value of the norm of with some length is as follows:

The most common usage of this is the Euclidean norm, also called the standard distance formula.

## Examples

- The one-norm is the sum of absolute values: This is like finding the distance from one place on a grid to another by summing together the distances in all directions the grid goes; see Manhattan Distance.
- Euclidean norm (also called L2-norm) is the sum of the squares of the values:
- Maximum norm is the maximum absolute value:
- When applied to matrices, the Euclidean norm is referred to as the Frobenius norm.
- L0 norm is the number of non-zero elements present in a vector.

## Related pages

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Norm (mathematics) Facts for Kids. *Kiddle Encyclopedia.*