Stage: 3 Challenge Level: 
Take a look at the two multiplications below. What do you notice?
$32 \times 46 = 1472$
$23 \times 64 = 1472$
The digits in this multiplication have been reversed, and the answer has stayed the same!
Is this surprising? Can you find other examples where this happens?
What do you notice about the pairs of two digit numbers that produce this special result?
Patterned numbers. Number - generally. Integers. Addition & subtraction. Properties of numbers. Mathematical reasoning & proof. Factors and multiples. Multiplication & division. Divisibility. Algebra - generally.
Published June 2000,February 2010.
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
