60http://nrich.maths.org/8684en 2012 http://nrich.maths.org/public/terms.phpPlay this game to learn about adding and subtracting positive and negative numbershttp://nrich.maths.org/9941Wed, 01 Dec 1999 00:00:01 +0000Imagine a very strange bank account where you are only allowed to do two things...http://nrich.maths.org/9923Mon, 01 Apr 2013 00:00:01 +0100http://nrich.maths.org/9920Mon, 01 Apr 2013 00:00:01 +0100Complex numbers can be represented graphically using an Argand diagram. This problem explains more...http://nrich.maths.org/9859Fri, 01 Feb 2013 00:00:01 +0000In this problem, we define complex numbers and invite you to explore what happens when you add and multiply them.http://nrich.maths.org/9858Fri, 01 Feb 2013 00:00:01 +0000What's the fairest way to choose 2 from 8 potential prize winners? How likely are you to be chosen?http://nrich.maths.org/9843Fri, 01 Mar 2013 00:00:01 +0000A practical experiment provides data. Moving onto expected results provides a context to establish the multiplication rule in probability, and an intuitive approach to conditional probability.http://nrich.maths.org/9840Tue, 01 Jan 2013 00:00:01 +0000I'm thinking of a rectangle with an area of 24. What could its perimeter be?http://nrich.maths.org/9691Sat, 01 Dec 2012 00:00:01 +0000A practical experiment which will introduce students to tree diagrams, and help them to understand that outcomes may not be equally likely.http://nrich.maths.org/9546Tue, 01 Jan 2013 00:00:01 +0000A practical experiment which uses tree diagrams to help students understand the nature of questions in conditional probability.http://nrich.maths.org/9525Tue, 01 Jan 2013 00:00:01 +0000What happens when we square complex numbers? Can the square of a complex number be real?http://nrich.maths.org/8109Fri, 01 Mar 2013 00:00:01 +0000Generate three random numbers to determine the side lengths of a triangle. What triangles can you draw?http://nrich.maths.org/8098Wed, 01 Aug 2012 00:00:01 +0100Have a go at creating these images based on circles. What do you notice about the areas of the different sections?http://nrich.maths.org/6468Tue, 01 Feb 2011 00:00:01 +0000Match the charts of these functions to the charts of their integrals.http://nrich.maths.org/6412Tue, 01 Feb 2011 00:00:01 +0000Can you find the area of the central part of this shape? Can you do it in more than one way?http://nrich.maths.org/6328Tue, 01 Feb 2011 00:00:01 +0000Different combinations of the weights available allow you to make different totals. Which totals can you make?http://nrich.maths.org/5958Tue, 01 Feb 2011 00:00:01 +0000How can we help students make sense of addition and subtraction of negative numbers?http://nrich.maths.org/5947Tue, 01 Feb 2011 00:00:01 +0000In this game the winner is the first to complete a row of three. Are some squares easier to land on than others?http://nrich.maths.org/5864Tue, 01 Feb 2011 00:00:01 +0000Can you picture how to order the cards to reproduce Charlie's card trick for yourself?http://nrich.maths.org/5775Tue, 01 Feb 2011 00:00:01 +0000If you have only 40 metres of fencing available, what is the maximum area of land you can fence off?http://nrich.maths.org/2663Sat, 01 Dec 2012 00:00:01 +0000How many moves does it take to swap over some red and blue frogs? Do you have a method?http://nrich.maths.org/1246Tue, 01 Feb 2011 00:00:01 +0000Charlie likes tablecloths that use as many colours as possible, but insists that his tablecloths have some symmetry. Can you work out how many colours he needs for different tablecloth designs?http://nrich.maths.org/900Wed, 01 Jun 2011 00:00:01 +0100