So you made it past the first door https://plus.google.com/101927319418268508510/posts/QksJVs8wiU7
As you enter the next room you see a room with 100 lockers number 1 through 100, and there are one 100 hundred people standing against one wall with a number on there shirt going from 1 through 100. The door to get out of this room has a number pad on it and you have to enter the right number to open it.
The wizard lets you know that each person will take turns opening or close the lockers the are divisible by there number on there shirt so the first one to go is the person with the 1 one his shirt and he opens all the lockers. After him goes the person with the number 2 one his shirt and he closes all the even lockers. The the person with the number three goes closing or opening every third locker, He would close locker 3 since it was open but open locker 6 since it was closed and so on. All 100 people will go. The Number to get out is the numbers in order of the lockers that are still open after everyone goes.
What is this number.
Extra kudos for anyone that can explain the mathematical reasoning behind the answer.
Also let me know in the comments if you would like me to continue this, even if you are not answering the riddles, and if you would like me to post the answer to the previous one when I post a new one, or how long you would like to wait for the answer, or if I should not post the answer