Definition:Vector Length/Real Number Line

Example of Vector Length
Let $\mathbf v$ be a vector represented by an arrow on the real number line.

Let:
 * the initial point of $\mathbf v$ be $a \in \R$
 * the terminal point of $\mathbf v$ be $b \in \R$

The length of $\mathbf v$ is defined as:
 * $\norm {\mathbf v} = \size {b - a}$

the absolute value of $b - a$.