School Lockers
  • A middle school has a hall with 1,000 lockers, all of which are closed. A thousand students start down the hall. The first student opens every locker. The second student closes all the lockers that are multiples of 2. The third student changes (closes an open locker or opens a closed one) all multiples of 3. The fourth student changes all multiples of 4. And so on. After all students have finished with the lockers, how many lockers are open?

Answer:    
  Please enter a numerical answer
(ex. 1,000 or 2.033) and click GO.		    

Contest problems and answers provided by:

David Rock
rock_david@colstate.edu
Columbus State University

Doug Brumbaugh
brumbad@pegasus.cc.ucf.edu
University of Central Florida