\chapter{آزمایشی}
\begin{latin}
There was, however, one significant difference between typing the manuscripts for Concrete Mathematics and for The Art of Computer Programming, caused by the fact that the Euler numerals 0123456789 are distinctly different from the numerals 0123456789 in ordinary text. [...] This experience ... taught me that there is a useful and meaningful distinction between text numerals and mathematical numerals. Text numerals are used in contexts like '1776' and 'Chapter 5' and '41 ways', where the numbers are essentially part of the English language; mathematical numerals, by contrast, are used in contexts like 'the greatest common divisor of 12 and 18 is 6', where the numbers are part of the mathematics. [...] Equation numbers presented us with one of the most perplexing design questions. Should those numbers be typeset in Euler or cast in Concrete? After several experiments we hit on a solution that must be right, because it seems so obvious in retrospect: We decided to set equation numbers in an "oldstyle" variant of Concrete Roman ..
\end{latin}