How many lockers are open?
21443
The locker problem - why squares?
24212
proving how many permutations exist.
22683
There are 10 stations on a circular path
115717
In how many ways can 4 unlabeled blue balls and 2 unlabeled red balls be packed in 5 different boxes?
140216
Finding multiple entries with binary search
137535
Close Vs Closed and Open Vs. Opened
144603
Are there any restrictions to the number of weapons a survivor can equip?
15349
Combinatorics riddle: keys and a safe
93459
Number of permutations of unspecified length
102590
What do I get for holding gyms?
23022
How much to store luggage at SFO for 24 hours?
80630
Αre there bathrooms on the Enterprise?
65617
What do the various locked door colors mean?
25457
FreeCell: How many cards can be moved at once?
8056
how to obtain a lock in two places but release on one place?
11460
Expected count of correct assignments
79978
What are the limits of the Room of Requirement?