There is a game board with the numbers 1 to 100 in ten rows. A transparent mask is placed on top of the board. The mask contains five holes and therefore leaves five numbers open.
A player now rolls a number of dice (4-7, depending on the location of the mask) and tries to calculate the open numbers by addition, subtraction, division and multiplication. If he or she manages to get to the right result, he or she places a chip on that number. The goal of the game is to get four or more chips in a row (each row of four counting two points, each additional chip in that row another point).
On http://perlhuhn.de/ziffernsheriff.html, Reinhold Wittig has published an alternative game to be played with the same game materials, called Ziffernsheriffs (in German only, so far).