Stage: 3 and 4 Challenge Level: 
Place value. Divisibility. Working systematically. Modulus arithmetic. Sequences. Factors and multiples. Powers & roots. Number bases. Index notation/Indices. Mathematical reasoning & proof.
Published January 1998,January 2007.
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