60Lower Secondary big button pagehttp://nrich.maths.org/secondary-loweren 2012 http://nrich.maths.org/public/terms.phpAddicted to Additionhttp://nrich.maths.org/11275Wed, 01 Dec 1999 00:00:01 +0000OverlapsCan you find ways to put numbers in the overlaps so the rings have equal totals?http://nrich.maths.org/11112Wed, 01 Dec 1999 00:00:01 +0000Forwards Add BackwardsWhat happens when you add a three digit number to its reverse?http://nrich.maths.org/11111Wed, 01 Dec 1999 00:00:01 +0000Add to 200By selecting digits for an addition grid, what targets can you make?http://nrich.maths.org/11110Wed, 01 Dec 1999 00:00:01 +0000ImpossibilitiesJust because a problem is impossible doesn't mean it's difficult...http://nrich.maths.org/11109Wed, 01 Dec 1999 00:00:01 +0000CryptarithmsCan you crack these cryptarithms?http://nrich.maths.org/11107Wed, 01 Dec 1999 00:00:01 +0000Combining LengthsHow many different lengths is it possible to measure with a set of three rods?http://nrich.maths.org/10897Thu, 01 May 2014 00:00:01 +0100Climbing the StairsIn how many ways can I get upstairs?http://nrich.maths.org/10871Thu, 01 May 2014 00:00:01 +0100You Can't Make an Omelette...Can you devise the most efficient strategy for finding the highest floor from which you can drop an egg safely?http://nrich.maths.org/10870Tue, 01 Apr 2014 00:00:01 +0100Going to the CinemaA cinema has 100 seats. Is it possible to fill every seat and take exactly £100?http://nrich.maths.org/10868Thu, 01 May 2014 00:00:01 +0100Estimating TimeHow well can you estimate 10 seconds? Investigate with our timing tool.http://nrich.maths.org/10629Sun, 01 Dec 2013 00:00:01 +0000Picturing the WorldHow can we make sense of national and global statistics involving very large numbers?http://nrich.maths.org/10464Tue, 01 Oct 2013 00:00:01 +0100Making Sense of Positives and NegativesThis article suggests some ways of making sense of calculations involving positive and negative numbers.http://nrich.maths.org/9958Wed, 01 May 2013 00:00:01 +0100Strange Bank Account (part 2)Investigate different ways of making £5 at Charlie's bank.http://nrich.maths.org/9943Wed, 01 May 2013 00:00:01 +0100Up, Down, Flying AroundPlay this game to learn about adding and subtracting positive and negative numbershttp://nrich.maths.org/9941Wed, 01 May 2013 00:00:01 +0100Strange Bank AccountImagine 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 +0100Constructing TrianglesGenerate 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 +0100Who's the Best?Which countries have the most naturally athletic populations?http://nrich.maths.org/7367Wed, 01 Jun 2011 00:00:01 +0100Always a Multiple?Think of a two digit number, reverse the digits, and add the numbers together. Something special happens...http://nrich.maths.org/7208Tue, 01 May 2012 00:00:01 +0100Dicey OperationsWho said that adding, subtracting, multiplying and dividing
couldn't be fun?http://nrich.maths.org/6606Tue, 01 Feb 2011 00:00:01 +0000Power Mad!Powers of numbers behave in surprising ways. Take a look at some of these and try to explain why they are true.http://nrich.maths.org/6401Tue, 01 Feb 2011 00:00:01 +0000Reaction TimerThis problem offers you two ways to test reactions - use them to
investigate your ideas about speeds of reaction.http://nrich.maths.org/6044Tue, 01 Feb 2011 00:00:01 +0000WeightsDifferent 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 +0000Playing Connect ThreeIn 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 +0000Difference SudokuUse the differences to find the solution to this Sudoku.http://nrich.maths.org/5798Sun, 01 Dec 2013 00:00:01 +0000ACE, TWO, THREE...Can 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 +0000Method in Multiplying Madness?Watch our videos of multiplication methods that you may not have met before. Can you make sense of them?http://nrich.maths.org/5612Sat, 01 Oct 2011 00:00:01 +0100FrogsHow 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 +0000Attractive TableclothsCharlie 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 +0100Two and TwoHow many solutions can you find to this sum? Each of the different letters stands for a different number.http://nrich.maths.org/781Tue, 01 Feb 2011 00:00:01 +0000