On the Subject of Bitmaps

Over 18 quintillion combinations, only some of them actually matter.

  • The module displays a bitmap of 64 pixels divided into four “quadrants”. Each pixel is bright (which we call “white” although it may be colored) or dark (“black”).
  • There are 4 buttons underneath, labeled 1, 2, 3, and 4.
  • In the following table, start at the rule whose number equals the last digit of the serial number.
  • Keep going through the rules (wrapping around if necessary) until you encounter a condition that applies.
  • Calculate the answer for the applicable rule. Repeatedly subtract 4 until the answer is between 1 and 4 and press the corresponding button to disarm the module.
#Rule
0If exactly one quadrant has 5 or fewer white pixels, the answer is the number of white pixels in the other 3 quadrants.
1If there are exactly as many mostly-white quadrants as there are lit indicators, the answer is the number of batteries.
2If exactly one row or column is completely white or completely black, the answer is its x-/y-coordinate (starting from 1 in the top/left).
3If there are fewer mostly-white quadrants than mostly-black quadrants, the answer is the number of mostly-black quadrants.
4If the entire bitmap has 36 or more white pixels, the answer is the total number of white pixels.
5If there are more mostly-white quadrants than mostly-black quadrants, the answer is the smallest number of black pixels in any quadrant.
6If exactly one quadrant has 5 or fewer black pixels, the answer is the number of black pixels in the other 3 quadrants.
7If there are exactly as many mostly-black quadrants as there are unlit indicators, the answer is the number of ports.
8If there is a 3×3 square that is completely white or completely black, the answer is the x-coordinate (starting from 1) of the center of the first such square in reading order.
9If there are exactly as many mostly-white quadrants as mostly-black quadrants, the answer is the first numeric digit of the serial number.