# 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.

# The Smith Jones Robinson Riddle - logic puzzle

On a train, Smith, Robinson, and Jones are the fireman, brakeman, and the engineer, but NOT respectively. Also aboard the train are three businessmen who have the same names: a Mr. Smith, a Mr. Robinson, and a Mr. Jones. Using the clues below, can you determine the identity of the Engineer?

1. Mr. Robinson lives in Detroit.

2. The brakeman lives exactly halfway between Chicago and Detroit.

3. Mr. Jones earns exactly $20,000 per year.

4. The brakeman's nearest neighbor, one of the passengers, earns exactly three times as much as the brakeman.

5. Smith beats the fireman in billiards.

6. The passenger whose name is the same as the brakeman's lives in Chicago.

1. Mr. Robinson lives in Detroit.

2. The brakeman lives exactly halfway between Chicago and Detroit.

3. Mr. Jones earns exactly $20,000 per year.

4. The brakeman's nearest neighbor, one of the passengers, earns exactly three times as much as the brakeman.

5. Smith beats the fireman in billiards.

6. The passenger whose name is the same as the brakeman's lives in Chicago.

# 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?