  To analyse the significance of the digits used for interval bounds, we
clarify the philosophical presuppositions of various interval notations. We use
information theory to determine the information content of the last digit of
the numeral used to denote the interval's bounds. This leads to the notion of
efficiency of a decimal digit: the actual value as percentage of the maximal
value of its information content. By taking this efficiency into account, many
presentations of intervals can be made more readable at the expense of
negligible loss of information.
