Skip to main content
Links to the University of Cambridge website
Links to the NRICH website Home page
Nurturing young mathematicians: teacher webinars
30 April (Primary)
,
1 May (Secondary)
menu
search
Teachers
expand_more
Early years
Primary
Secondary
Post-16
Events
Professional development
Students
expand_more
Primary
Secondary
Post-16
Parents
expand_more
Early Years
Primary
Secondary
Post-16
Problem-solving Schools
About NRICH
expand_more
About us
Impact stories
Support us
Our funders
Contact us
search
Site search
search
Or search by topic
Number and algebra
The Number System and Place Value
Calculations and Numerical Methods
Fractions, Decimals, Percentages, Ratio and Proportion
Properties of Numbers
Patterns, Sequences and Structure
Algebraic expressions, equations and formulae
Coordinates, Functions and Graphs
Geometry and measure
Angles, Polygons, and Geometrical Proof
3D Geometry, Shape and Space
Measuring and calculating with units
Transformations and constructions
Pythagoras and Trigonometry
Vectors and Matrices
Probability and statistics
Handling, Processing and Representing Data
Probability
Working mathematically
Thinking mathematically
Mathematical mindsets
For younger learners
Early Years Foundation Stage
Advanced mathematics
Decision Mathematics and Combinatorics
Advanced Probability and Statistics
Mechanics
Calculus
The Best Card Trick?
Age
11 to 16
Challenge Level
Problem
Getting Started
Student Solutions
Teachers' Resources
In the video below, you can see Alison and Charlie performing a card trick for Yanqing:
Can you figure out how Alison and Charlie's code works?
The video below shows two more examples of the trick; do these examples confirm your initial ideas about the code?
This crib sheet
fell out of Charlie's pocket after he had performed the trick.
Can you use it to make sense of the code?
Find someone to work with, and together practise the trick until you can impress someone with your mathemagical skills!
Alternatively, if you are working on your own, here are sets of five cards that might be handed to you:
For each set, work out which four cards you would show, and in which order, so that a partner could work out the fifth card.
Notes and Background
This trick first appears in Wallace Lee's book "Math Miracles" in which he credits its invention to William Fitch Cheney, Jr., a.k.a. "Fitch."
You can read an article by Michael Kleber, the first part of which describes the trick,
here
.