Welcome to MindCipher, a social repository of the world's greatest brain teasers, logic puzzles and mental challenges.

Filtered by tag: logical

13 100 Light Bulbs
There are 100 light switches, all of them are off. First, you walk by them, turning all of them on. Next, you walk by them turning every other one off. Then, you walk by them changing every third on ...
mathematical logical Submitted by Aakash
Hard
7.7