Skip over navigation
Cambridge University Faculty of Mathematics NRich logo
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

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
  • Developing positive attitudes
  • Cross-curricular contexts

Advanced mathematics

  • Decision Mathematics and Combinatorics
  • Advanced Probability and Statistics
  • Mechanics
  • Calculus

For younger learners

  • Early Years Foundation Stage

Solving Together - Combining Lengths

Age 11 to 14

In this puzzle, work together to explore the lengths you can make using three rods.
Watch the video for an introduction, or scroll down to explore.



Alternatively, here are some instructions.

Take it in turns to choose three rods, and see which lengths you can make with them.
Can you find a set of three rods that you can use to make any length from 1 to 10?





It's possible to find a set of rods that measures even more than ten different lengths.
Can you find a set of three rods that you can use to make any length from 1 to 11? Or 1 to 12?
What's the furthest that you can go?


How many different lengths could you make if you only had two rods?
How many different lengths do you think you could make using four rods?


Note for parents: You may find it useful to watch our Guidance for Parents video for advice on how to get the most out of the Solving Together resources.

Combining Lengths explores the mathematical areas of combinatorics and ternary arithmetic. It builds important problem solving skills, such as working systematically.

 

  • Tech help
  • Accessibility Statement
  • Sign up to our newsletter
  • Twitter X logo

The NRICH Project aims to enrich the mathematical experiences of all learners. To support this aim, members of the NRICH team work in a wide range of capacities, including providing professional development for teachers wishing to embed rich mathematical tasks into everyday classroom practice.

NRICH is part of the family of activities in the Millennium Mathematics Project.

University of Cambridge logo NRICH logo