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Real value
A real value can geometrically be represented by a point on the real line.
Explanation
We can imagine what a real value is. It is a number with one dimension.
For real number, we know the concepts of greater than (>) and less than (<). This indication is not possible for multidimensional numbers. So it does not apply to complex numbers with two dimensions, and quaternions with four dimensions, and octonions with eight dimensions.
Examples
Real values are 1, −2, 0, √3, π, ¾ etc. The imaginary unit i has no real value, and infinitely large ∞ and infinitely small Δx are no numbers.