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Resources tagged with Working systematically similar to History Mystery:

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Broad Topics > Using, Applying and Reasoning about Mathematics > Working systematically

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Diagonal Sums Sudoku

Stage: 2, 3 and 4 Challenge Level: Challenge Level:1

Solve this Sudoku puzzle whose clues are in the form of sums of the numbers which should appear in diagonal opposite cells.

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You Owe Me Five Farthings, Say the Bells of St Martin's

Stage: 3 Challenge Level: Challenge Level:2 Challenge Level:2

Use the interactivity to listen to the bells ringing a pattern. Now it's your turn! Play one of the bells yourself. How do you know when it is your turn to ring?

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Intersection Sudoku 2

Stage: 3 and 4 Challenge Level: Challenge Level:1

A Sudoku with a twist.

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Ratio Sudoku 1

Stage: 3 and 4 Challenge Level: Challenge Level:2 Challenge Level:2

A Sudoku with clues as ratios.

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Wallpaper Sudoku

Stage: 3 and 4 Challenge Level: Challenge Level:1

A Sudoku that uses transformations as supporting clues.

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Tetrahedra Tester

Stage: 3 Challenge Level: Challenge Level:3 Challenge Level:3 Challenge Level:3

An irregular tetrahedron is composed of four different triangles. Can such a tetrahedron be constructed where the side lengths are 4, 5, 6, 7, 8 and 9 units of length?

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Twin Corresponding Sudoku

Stage: 3, 4 and 5 Challenge Level: Challenge Level:1

This sudoku requires you to have "double vision" - two Sudoku's for the price of one

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Intersection Sums Sudoku

Stage: 2, 3 and 4 Challenge Level: Challenge Level:1

A Sudoku with clues given as sums of entries.

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Ratio Sudoku 3

Stage: 3 and 4 Challenge Level: Challenge Level:1

A Sudoku with clues as ratios or fractions.

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Seasonal Twin Sudokus

Stage: 3 and 4 Challenge Level: Challenge Level:1

This pair of linked Sudokus matches letters with numbers and hides a seasonal greeting. Can you find it?

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Triangles to Tetrahedra

Stage: 3 Challenge Level: Challenge Level:3 Challenge Level:3 Challenge Level:3

Starting with four different triangles, imagine you have an unlimited number of each type. How many different tetrahedra can you make? Convince us you have found them all.

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Corresponding Sudokus

Stage: 3, 4 and 5

This second Sudoku article discusses "Corresponding Sudokus" which are pairs of Sudokus with terms that can be matched using a substitution rule.

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Twin Corresponding Sudokus II

Stage: 3 and 4 Challenge Level: Challenge Level:1

Two sudokus in one. Challenge yourself to make the necessary connections.

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Quadruple Clue Sudoku

Stage: 3 and 4 Challenge Level: Challenge Level:1

Four numbers on an intersection that need to be placed in the surrounding cells. That is all you need to know to solve this sudoku.

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Ratio Sudoku 2

Stage: 3 and 4 Challenge Level: Challenge Level:1

A Sudoku with clues as ratios.

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Twin Corresponding Sudoku III

Stage: 3 and 4 Challenge Level: Challenge Level:2 Challenge Level:2

Two sudokus in one. Challenge yourself to make the necessary connections.

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Intersection Sudoku 1

Stage: 3 and 4 Challenge Level: Challenge Level:2 Challenge Level:2

A Sudoku with a twist.

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When Will You Pay Me? Say the Bells of Old Bailey

Stage: 3 Challenge Level: Challenge Level:3 Challenge Level:3 Challenge Level:3

Use the interactivity to play two of the bells in a pattern. How do you know when it is your turn to ring, and how do you know which bell to ring?

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Product Sudoku 2

Stage: 3 and 4 Challenge Level: Challenge Level:1

Given the products of diagonally opposite cells - can you complete this Sudoku?

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The Naked Pair in Sudoku

Stage: 2, 3 and 4

A particular technique for solving Sudoku puzzles, known as "naked pair", is explained in this easy-to-read article.

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Another Quadruple Clue Sudoku

Stage: 3 and 4 Challenge Level: Challenge Level:1

This is a variation of sudoku which contains a set of special clue-numbers. Each set of 4 small digits stands for the numbers in the four cells of the grid adjacent to this set.

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More Magic Potting Sheds

Stage: 3 Challenge Level: Challenge Level:3 Challenge Level:3 Challenge Level:3

The number of plants in Mr McGregor's magic potting shed increases overnight. He'd like to put the same number of plants in each of his gardens, planting one garden each day. How can he do it?

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Introducing NRICH TWILGO

Stage: 1, 2, 3, 4 and 5 Challenge Level: Challenge Level:1

We're excited about this new program for drawing beautiful mathematical designs. Can you work out how we made our first few pictures and, even better, share your most elegant solutions with us?

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Quadruple Sudoku

Stage: 3 and 4 Challenge Level: Challenge Level:2 Challenge Level:2

Four small numbers give the clue to the contents of the four surrounding cells.

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Squares in Rectangles

Stage: 3 Challenge Level: Challenge Level:2 Challenge Level:2

A 2 by 3 rectangle contains 8 squares and a 3 by 4 rectangle contains 20 squares. What size rectangle(s) contain(s) exactly 100 squares? Can you find them all?

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Equation Sudoku

Stage: 3, 4 and 5 Challenge Level: Challenge Level:1

Solve the equations to identify the clue numbers in this Sudoku problem.

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Sandwiches

Stage: 2, 3, 4 and 5 Challenge Level: Challenge Level:3 Challenge Level:3 Challenge Level:3

Arrange the digits 1, 1, 2, 2, 3 and 3 so that between the two 1's there is one digit, between the two 2's there are two digits, and between the two 3's there are three digits.

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Integrated Product Sudoku

Stage: 3 and 4 Challenge Level: Challenge Level:1

This Sudoku puzzle can be solved with the help of small clue-numbers on the border lines between pairs of neighbouring squares of the grid.

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Bochap Sudoku

Stage: 3 and 4 Challenge Level: Challenge Level:2 Challenge Level:2

This Sudoku combines all four arithmetic operations.

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Rectangle Outline Sudoku

Stage: 3 and 4 Challenge Level: Challenge Level:2 Challenge Level:2

Each of the main diagonals of this sudoku must contain the numbers 1 to 9 and each rectangle width the numbers 1 to 4.

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Summing Consecutive Numbers

Stage: 3 Challenge Level: Challenge Level:1

Many numbers can be expressed as the sum of two or more consecutive integers. For example, 15=7+8 and 10=1+2+3+4. Can you say which numbers can be expressed in this way?

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Integrated Sums Sudoku

Stage: 3 and 4 Challenge Level: Challenge Level:1

The puzzle can be solved with the help of small clue-numbers which are either placed on the border lines between selected pairs of neighbouring squares of the grid or placed after slash marks on. . . .

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Isosceles Triangles

Stage: 3 Challenge Level: Challenge Level:1

Draw some isosceles triangles with an area of $9$cm$^2$ and a vertex at (20,20). If all the vertices must have whole number coordinates, how many is it possible to draw?

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Addition Equation Sudoku

Stage: 3, 4 and 5 Challenge Level: Challenge Level:1

You need to find the values of the stars before you can apply normal Sudoku rules.

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Product Doubles Sudoku

Stage: 3 and 4 Challenge Level: Challenge Level:1

Each clue number in this sudoku is the product of the two numbers in adjacent cells.

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Colour Islands Sudoku 2

Stage: 3, 4 and 5 Challenge Level: Challenge Level:1

In this Sudoku, there are three coloured "islands" in the 9x9 grid. Within each "island" EVERY group of nine cells that form a 3x3 square must contain the numbers 1 through 9.

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An Introduction to Magic Squares

Stage: 1, 2, 3 and 4

Find out about Magic Squares in this article written for students. Why are they magic?!

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Shady Symmetry

Stage: 3 Challenge Level: Challenge Level:1

How many different symmetrical shapes can you make by shading triangles or squares?

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Games Related to Nim

Stage: 1, 2, 3 and 4

This article for teachers describes several games, found on the site, all of which have a related structure that can be used to develop the skills of strategic planning.

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Pole Star Sudoku 2

Stage: 3 and 4 Challenge Level: Challenge Level:2 Challenge Level:2

This Sudoku, based on differences. Using the one clue number can you find the solution?

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Maths Trails

Stage: 2 and 3

The NRICH team are always looking for new ways to engage teachers and pupils in problem solving. Here we explain the thinking behind maths trails.

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Advent Sudoku

Stage: 3 Challenge Level: Challenge Level:1

Rather than using the numbers 1-9, this sudoku uses the nine different letters used to make the words "Advent Calendar".

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Extra Challenges from Madras

Stage: 3 Challenge Level: Challenge Level:2 Challenge Level:2

A few extra challenges set by some young NRICH members.

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Sticky Numbers

Stage: 3 Challenge Level: Challenge Level:1

Can you arrange the numbers 1 to 17 in a row so that each adjacent pair adds up to a square number?

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Four Triangles Puzzle

Stage: 1 and 2 Challenge Level: Challenge Level:3 Challenge Level:3 Challenge Level:3

Cut four triangles from a square as shown in the picture. How many different shapes can you make by fitting the four triangles back together?

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More on Mazes

Stage: 2 and 3

There is a long tradition of creating mazes throughout history and across the world. This article gives details of mazes you can visit and those that you can tackle on paper.

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Cinema Problem

Stage: 3 and 4 Challenge Level: Challenge Level:1

A cinema has 100 seats. Show how it is possible to sell exactly 100 tickets and take exactly £100 if the prices are £10 for adults, 50p for pensioners and 10p for children.

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Where Can We Visit?

Stage: 3 Challenge Level: Challenge Level:2 Challenge Level:2

Charlie and Abi put a counter on 42. They wondered if they could visit all the other numbers on their 1-100 board, moving the counter using just these two operations: x2 and -5. What do you think?

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Arrangements

Stage: 2 Challenge Level: Challenge Level:1

Is it possible to place 2 counters on the 3 by 3 grid so that there is an even number of counters in every row and every column? How about if you have 3 counters or 4 counters or....?

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Consecutive Negative Numbers

Stage: 3 Challenge Level: Challenge Level:3 Challenge Level:3 Challenge Level:3

Do you notice anything about the solutions when you add and/or subtract consecutive negative numbers?