Exploring Our Number System
The Remainders Game
Play this game and see if you can figure out the computer's chosen number.
Got It
A game for two people, or play online. Given a target number, say 23, and a range of numbers to choose from, say 1-4, players take it in turns to add to the running total to hit their target.
Factors and Multiples Game
A game in which players take it in turns to choose a number. Can you block your opponent?
What Numbers Can We Make?
Imagine we have four bags containing a large number of 1s, 4s, 7s and 10s. What numbers can we make?
American Billions
Play the divisibility game to create numbers in which the first two digits make a number divisible by 2, the first three digits make a number divisible by 3...
How Much Can We Spend?
A country has decided to have just two different coins, 3z and 5z coins. Which totals can be made? Is there a largest total that cannot be made? How do you know?
Weights
Different combinations of the weights available allow you to make different totals. Which totals can you make?
Reversals
Where should you start, if you want to finish back where you started?
Stars
Can you work out what step size to take to ensure you visit all the dots on the circle?
Legs Eleven
Take any four digit number. Move the first digit to the end and move the rest along. Now add your two numbers. Did you get a multiple of 11?
Always a Multiple?
Think of a two digit number, reverse the digits, and add the numbers together. Something special happens...
Differences
Can you guarantee that, for any three numbers you choose, the product of their differences will always be an even number?
Combining Lengths
How many different lengths is it possible to measure with a set of three rods?
Divisibility Tests
This article explains various divisibility rules and why they work. An article to read with pencil and paper handy.
Charlie's Delightful Machine
Here is a machine with four coloured lights. Can you develop a strategy to work out the rules controlling each light?
Take Three from Five
Caroline and James pick sets of five numbers. Charlie tries to find three that add together to make a multiple of three. Can they stop him?
Product Sudoku
The clues for this Sudoku are the product of the numbers in adjacent squares.
Factorising with Multilink
Can you find out what is special about the dimensions of rectangles you can make with squares, sticks and units?
Puzzling Place Value
Can you explain what is going on in these puzzling number tricks?