60Lower Secondary big button pagehttp://nrich.maths.org/secondary-loweren 2012 http://nrich.maths.org/public/terms.phpThe Simple LifeThe answer is $5x+8y$... What was the question?http://nrich.maths.org/13207Wed, 01 Dec 1999 00:00:01 +0000Almost OneChoose some fractions and add them together. Can you get close to 1?http://nrich.maths.org/13205Wed, 01 Dec 1999 00:00:01 +0000Alison's QuiltNine squares are fitted together to form a rectangle. Can you find its dimensions?http://nrich.maths.org/13124Tue, 01 Feb 2011 00:00:01 +0000Number FamiliesHow many different number families can you find?http://nrich.maths.org/13123Tue, 01 Feb 2011 00:00:01 +0000Shape ProductsThese eleven shapes each stand for a different number. Can you use the multiplication sums to work out what they are?http://nrich.maths.org/13079Tue, 01 Feb 2011 00:00:01 +0000Red Card Blue CardCan you arrange the red and blue cards so that the rules are all followed?http://nrich.maths.org/12808Wed, 01 Dec 1999 00:00:01 +0000More Isometric AreasIsometric Areas explored areas of parallelograms in triangular units. Here we explore areas of triangles...http://nrich.maths.org/11854Wed, 01 Dec 1999 00:00:01 +0000Isometric AreasWe usually use squares to measure area, but what if we use triangles instead?http://nrich.maths.org/11853Wed, 01 Dec 1999 00:00:01 +0000Angles in Three SquaresDrawing the right diagram can help you to prove a result about the angles in a line of squares.http://nrich.maths.org/11852Wed, 01 Dec 1999 00:00:01 +0000Common Remainder144 divided by n leaves a remainder of 11. 220 divided by n also leaves a remainder of 11. What is n?http://nrich.maths.org/11715Fri, 01 Sep 2017 00:00:01 +0100Equal MeansWhat value of x makes the mean of the first three numbers in this list equal to the mean of the other four?http://nrich.maths.org/11697Fri, 01 Sep 2017 00:00:01 +0100An Equilateral Triangular ProblemTake an equilateral triangle and cut it into smaller pieces. What can you do with them?http://nrich.maths.org/11501Wed, 01 Dec 1999 00:00:01 +0000Polygon PicturesCan you work out how these polygon pictures were drawn, and use that to figure out their angles?http://nrich.maths.org/11498Wed, 01 Dec 1999 00:00:01 +0000Star PolygonsDraw some stars and measure the angles at their points. Can you find and prove a result about their sum?http://nrich.maths.org/11456Wed, 01 Dec 1999 00:00:01 +0000Towering TrapeziumsCan you find the areas of the trapezia in this sequence?http://nrich.maths.org/11449Sun, 01 Mar 2015 00:00:01 +0000Hollow SquaresWhich armies can be arranged in hollow square fighting formations?http://nrich.maths.org/11257Mon, 01 Sep 2014 00:00:01 +0100Difference of Two SquaresWhat is special about the difference between squares of numbers adjacent to multiples of three?http://nrich.maths.org/11120Mon, 01 Sep 2014 00:00:01 +0100Pythagoras PerimetersIf you know the perimeter of a right angled triangle, what can you say about the area?http://nrich.maths.org/11106Mon, 01 Sep 2014 00:00:01 +0100Quadratic PatternsSurprising numerical patterns can be explained using algebra and diagrams...http://nrich.maths.org/11011Mon, 01 Sep 2014 00:00:01 +0100Magic 7Can you complete this magic square with the numbers from 7 to 15?http://nrich.maths.org/10184Tue, 01 Sep 2015 00:00:01 +0100Cyclic QuadrilateralsDraw some quadrilaterals on a 9-point circle and work out the angles. Is there a theorem?http://nrich.maths.org/6624Tue, 01 Feb 2011 00:00:01 +0000Multiples SudokuEach clue in this Sudoku is the product of the two numbers in adjacent cells.http://nrich.maths.org/6434Tue, 01 Feb 2011 00:00:01 +0000Trapezium ArchWeekly Problem 27 - 2007<br />
Ten stones form an arch. What is the size of the smallest angles of the trapezoidal stones?http://nrich.maths.org/5670Sun, 01 Jul 2007 00:00:01 +0100Triangles in CirclesCan you find triangles on a 9-point circle? Can you work out their angles?http://nrich.maths.org/2844Tue, 01 Feb 2011 00:00:01 +0000Of All the AreasCan you find a general rule for finding the areas of equilateral triangles drawn on an isometric grid?http://nrich.maths.org/693Tue, 01 Feb 2011 00:00:01 +0000Counting FactorsIs there an efficient way to work out how many factors a large number has?http://nrich.maths.org/480Tue, 01 Feb 2011 00:00:01 +0000Latin NumbersCan you create a Latin Square from multiples of a six digit number?http://nrich.maths.org/434Tue, 01 Feb 2011 00:00:01 +0000Rationals Between...What fractions can you find between the square roots of 65 and 67?http://nrich.maths.org/344Tue, 01 Feb 2011 00:00:01 +0000Gift of GemsFour jewellers share their stock. Can you work out the relative values of their gems?http://nrich.maths.org/330Tue, 01 Feb 2011 00:00:01 +0000Building TetrahedraCan you make a tetrahedron whose faces all have the same perimeter?http://nrich.maths.org/272Tue, 01 Feb 2011 00:00:01 +0000Calendar CapersChoose any three by three square of dates on a calendar page...http://nrich.maths.org/85Tue, 01 Feb 2011 00:00:01 +0000