# Lockers - math puzzle

A high school has a strange principal. On the first day, he has his students perform an odd opening day ceremony:

There are one thousand lockers and one thousand students in the school. The principal asks the first student to go to every locker and open it. Then he has the second student go to every second locker and close it. The third goes to every third locker and, if it is closed, he opens it, and if it is open, he closes it. The fourth student does this to every fourth locker, and so on. After the process is completed with the thousandth student, how many lockers are open?

There are one thousand lockers and one thousand students in the school. The principal asks the first student to go to every locker and open it. Then he has the second student go to every second locker and close it. The third goes to every third locker and, if it is closed, he opens it, and if it is open, he closes it. The fourth student does this to every fourth locker, and so on. After the process is completed with the thousandth student, how many lockers are open?

# Self Ref - math puzzle

Find a number ABCDEFGHIJ such that A is the count of how many 0's are in the number, B is the number of 1's, and so on.

# Horse friends - math puzzle

Three horses are standing in a triangular field, which is exactly 100
yards on each side. One horse stands at each corner; and simultaneously
all three set off running. Each horse runs after the horse in the
adjacent corner on his left, thus following a curved course, which
terminates in the middle of the field, all three horses arriving there
together.
The horses obviously ran at the same speed, but just how far did they
run?