function y = pages(n)
% This function will convert n pages to digits.
% In a "function" statement, the "y" is just a dummy output
% variable, but, unfortunately, we must put something there!
% The input variable is clearly "n".
% We must name this file:  Pages.m
% When we execute it (from the workspace), we simply type:
% Pages(12)  [in the Command Window!]
%
% Example:  If n = 12, then the first 9 pages will have one digit
% (9 digits so far), and then the remaining 3 pages will have two
% digits (6 more digits), for a total of 15 digits used to number
% the pages.
%
% We start with one (level one) digit pages.  We haven't processed
% any pages yet, so digits = 0, for now.
level = 1;
digits = 0;
% We *only* execute the statements between the "while" and the "end"
% when there are "too many" pages to process.  That is, if the
% remaining number of pages is greater than the max. number of pages
% at a particular level, then do the stated processing!
while (n > 0.9*10^level)
    % We process an entire level!
    % Remember?  It was 9 digits for the first level,
    % 90 digits for the second, 900 for the third, etc.
    % We *subtract* off the number of pages we plan to process
    % during this iteration.
    n = n - 0.9*10^level;
    % Add the number of digits for this level.
    digits = digits + level*(0.9*10^level);
    % Increment the level number for the next pass.
    level = level + 1;
end
% We now process the "leftover" pages.  Each page has (level) digits.
digits = digits + level*n;
% Print out the answer!
fprintf('We used %6d digits!\n',digits);