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
Prompt Cards
Age
7 to 11
Challenge Level
Problem
Student Solutions
Teachers' Resources
Can you work out what Charlie's number is from these clues?
C1: Charlie's number is palindromic, the second and third numbers are different.
C2: Charlie's number is greater than 100 and is prime.
C3: Charlie's number is odd. The difference between the largest and smallest digits is 5.
C4: Charlie's number is less than 1000. The sum of the digits is 14.
C5: Charlie's number is not divisible by 3. It is less than 500.
C6: Charlie's number is a whole number with only two divisors.
Now can you make this tower from coloured cubes? Or, if you don't have any cubes, you could draw it.
C1: There are six blocks in the tower, a yellow one is at the top.
C2: The red block is above the green block.
C3: One of the yellow blocks is above the green block, the other is below it.
C4: Each of the blue blocks shares a face with the green block.
C5: No two blocks of the same colour touch each other.
C6: There are no brown blocks in the tower.