text figures

Some fonts have a text figures variant of the digits 0 to 9 where some of them have ascenders and some have descenders so that they blend better with the general text. Here is Champernowne’s constant $C_{10}$ to 9 decimal places written in Georgia:

Usually, 6 and 8 have ascenders, 3, 4, 5, 7 and 9 have descenders. Since most texts use base 10 numbers, and each digit usually occurs in about the same proportion as the other digits, this means that numbers have varying heights in just about the same propoertions as the words in the text. Using text figures for base 3 numbers would result in numbers always lacking in ascenders and descenders. For mathematical books and papers, however, text figures are generally eschewed.