Stage: 3 Challenge Level: 
Find the smallest whole number which, when mutiplied by 7, gives a product consisting entirely of ones.
Simultaneous equations. Visualising. Working systematically. Divisibility. Factors and multiples. Generalising. Addition & subtraction. Games. Multiplication & division. Interactivities.
Published June 2000.
Copyright © 2007. University of Cambridge. All rights reserved.
NRICH is part of the family of activities in the Millennium Mathematics Project, which also includes the Plus and Motivate sites.
email: nrich@damtp.cam.ac.uk
