### Real number

Numbers with *one* dimension are called **real numbers**. You write them as

x=x_{0}e_{0}

and they consist of the real number *x*_{0} and the unit

{e_{0}}

##### Explanation

When multiplying the unit { *e*_{0}} only { *e*_{0}} can arise, so

× e_{0}e_{0}e_{0}

The unit *e*_{0} is the real number 1.

For real numbers, we know the concept of greater than (>) and less than (<). This indication is not possible for multidimensional numbers. So it is not possible for complex numbers with *two* dimensions, and quaternions with *four* dimensions and octonions with *eight* dimensions.

## HistoryThis notation was proposed in 1844 by the German mathematician Hermann Grassmann, who developed linear algebra. |