 ## 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 (add/subtract 10 to bring into the range 0–9).
• Keep going through the rules (wrapping around if necessary) until you encounter a condition that applies.
• Calculate the answer for the applicable rule. Repeatedly add or 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).