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There are 20 NRICH Mathematical resources connected to DMC Exploring our number system, you may find related items under Developing mathematical creativity.
Broad Topics > Developing mathematical creativity > DMC Exploring our number systemCan you explain what is going on in these puzzling number tricks?
Where should you start, if you want to finish back where you started?
Can you find out what is special about the dimensions of rectangles you can make with squares, sticks and units?
Imagine we have four bags containing a large number of 1s, 4s, 7s and 10s. What numbers can we make?
Think of a two digit number, reverse the digits, and add the numbers together. Something special happens...
Here is a machine with four coloured lights. Can you develop a strategy to work out the rules controlling each light?
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?
Play this game and see if you can figure out the computer's chosen number.
Different combinations of the weights available allow you to make different totals. Which totals can you make?
A game in which players take it in turns to choose a number. Can you block your opponent?
The clues for this Sudoku are the product of the numbers in adjacent squares.
Can you work out what step size to take to ensure you visit all the dots on the circle?
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?
This article explains various divisibility rules and why they work. An article to read with pencil and paper handy.
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.
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...
Can you guarantee that, for any three numbers you choose, the product of their differences will always be an even number?
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?
How many different lengths is it possible to measure with a set of three rods?