No one would ever expect mathematics to show up in a zombie survival game. Still, we all know that Techland loves to include a few intriguing puzzles in its post-apocalyptic series. By now, you might’ve noticed that there are a few safes around Castor Woods that are unmarked and don’t start a quest at all. However, they contain some useful materials and, in some rare cases, even weapon mods that you can craft. One of those is the safe that has a code involving mathematics, and one of the most creative ones to crack in Dying Light: The Beast.
Mathematics Safe Location and Solution
The mathematics safe (which is how we decided to call it here) of Dying Light: The Beast is located just next to the green hotel in Old Town. If you don’t know where it is exactly, you can see the image below for its precise location.

You’ll have to jump through a window, and you’ll locate it more easily if you use your Survivor Instinct, as it will mark the safe with a golden treasure icon.
Once inside the building, you’ll notice a harrowing scene with two dead zombies, a whiteboard, and a note. First, grab the note and read it.

The clue mentions how the person wanted to see how advanced the cognitive skills of the infected were, and to do that, they decided to make a small test involving mathematics and UV light. With that in mind, turn toward the whiteboard, equip your UV light, and aim it at the object.

The UV light will illuminate the whiteboard, showing the following mathematical operations:
- 25 – 10 =
- 11 x 2 =
- 51 – 11 =
To speed up the process, we’ll solve them for you. The results of each one, in the above order, areย 15, 22, 40, which, you guessed it, is the safe’s code.

Once you have it, return to the safe to input the code and open it. You will get the Puff weapon mod, which you’ll now be able to craft at any workbench. While it doesn’t give you any extra stuff like legendary things to sell or a healing item, the mod is quite good, as it adds Blast to the tip of some weapons.