## On the Subject of Warning Signs

It's much easier to not screw up if you haven't screwed up already.

DANGER! This module shows a large sign to warn you about a specific hazard. To disarm the module, detach the sign by unscrewing its screws, one at a time, when the *last seconds digit of the countdown timer* is a valid digit.

Get three valid timer digits by following these steps:

- Construct a triangle as shown in the diagram by filling in the digits 0 to 9. Start with the
*first digit of the serial number*at the top and continue in reading order, increasing each subsequent digit by 1. Wrap back to 0 if you exceed 9. -
Receive a number from
*Table SGN*by using the hazard shown on the sign and the correct column following these rules:- If the number of unsolved* modules is a multiple of 4 use column D.
- Otherwise, if the number of unsolved* modules is a multiple of 3 use column A.
- Otherwise, if the number of unsolved* modules is a multiple of 2 use column N.
- Otherwise, use column G.

* this includes needy modules.

- In the triangle, find all possible equilateral triangles in which the received number appears in a corner position. Then, locate the three numbers that
*don't appear in corner positions*of these triangles.

#### Unscrewing a screw is valid if the last seconds digit of the countdown timer matches one of these three numbers.

**NOTE:** Make sure to unscrew one screw for every valid timer digit. Moreover, the whole process cannot exceed 9 timer ticks from the first unscrew. Taking too long or unscrewing on an invalid timer digit will result in a strike.