# Resources tagged with: Working systematically

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Broad Topics > Thinking Mathematically > Working systematically

##### Age 11 to 14Challenge Level

Replace the letters with numbers to make the addition work out correctly. R E A D + T H I S = P A G E

### Special Numbers

##### Age 11 to 14Challenge Level

My two digit number is special because adding the sum of its digits to the product of its digits gives me my original number. What could my number be?

### Gabriel's Problem

##### Age 11 to 14Challenge Level

Gabriel multiplied together some numbers and then erased them. Can you figure out where each number was?

##### Age 11 to 14Challenge Level

If you take a three by three square on a 1-10 addition square and multiply the diagonally opposite numbers together, what is the difference between these products. Why?

### Maths Trails

##### Age 7 to 14

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.

### Summing Consecutive Numbers

##### Age 11 to 14Challenge Level

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

### Window Frames

##### Age 5 to 14Challenge Level

This task encourages you to investigate the number of edging pieces and panes in different sized windows.

### Alphabetti Sudoku

##### Age 11 to 16Challenge Level

This Sudoku requires you to do some working backwards before working forwards.

### Games Related to Nim

##### Age 5 to 16

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.

### 9 Weights

##### Age 11 to 14Challenge Level

You have been given nine weights, one of which is slightly heavier than the rest. Can you work out which weight is heavier in just two weighings of the balance?

### Sticky Numbers

##### Age 11 to 14Challenge Level

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

### Football Sum

##### Age 11 to 14Challenge Level

Find the values of the nine letters in the sum: FOOT + BALL = GAME

##### Age 11 to 14Challenge Level

By selecting digits for an addition grid, what targets can you make?

### Consecutive Negative Numbers

##### Age 11 to 14Challenge Level

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

### Charitable Pennies

##### Age 7 to 14Challenge Level

Investigate the different ways that fifteen schools could have given money in a charity fundraiser.

### Two and Two

##### Age 11 to 16Challenge Level

How many solutions can you find to this sum? Each of the different letters stands for a different number.

### Cayley

##### Age 11 to 14Challenge Level

The letters in the following addition sum represent the digits 1 ... 9. If A=3 and D=2, what number is represented by "CAYLEY"?

### Colour Islands Sudoku

##### Age 11 to 14Challenge Level

An extra constraint means this Sudoku requires you to think in diagonals as well as horizontal and vertical lines and boxes of nine.

### More Magic Potting Sheds

##### Age 11 to 14Challenge Level

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?

### Two Egg Timers

##### Age 7 to 11Challenge Level

You have two egg timers. One takes 4 minutes exactly to empty and the other takes 7 minutes. What times in whole minutes can you measure and how?

### Star Product Sudoku

##### Age 11 to 16Challenge Level

The puzzle can be solved by finding the values of the unknown digits (all indicated by asterisks) in the squares of the $9\times9$ grid.

##### Age 11 to 16Challenge Level

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.

### Six Is the Sum

##### Age 7 to 11Challenge Level

What do the digits in the number fifteen add up to? How many other numbers have digits with the same total but no zeros?

### Coded Hundred Square

##### Age 7 to 11Challenge Level

This 100 square jigsaw is written in code. It starts with 1 and ends with 100. Can you build it up?

### Prison Cells

##### Age 7 to 11Challenge Level

There are 78 prisoners in a square cell block of twelve cells. The clever prison warder arranged them so there were 25 along each wall of the prison block. How did he do it?

### Multiples Sudoku

##### Age 11 to 14Challenge Level

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

##### Age 11 to 16Challenge Level

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.

### Where Can We Visit?

##### Age 11 to 14Challenge Level

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?

### Intersection Sudoku 2

##### Age 11 to 16Challenge Level

A Sudoku with a twist.

### Trebling

##### Age 7 to 11Challenge Level

Can you replace the letters with numbers? Is there only one solution in each case?

### Number Daisy

##### Age 11 to 14Challenge Level

Can you find six numbers to go in the Daisy from which you can make all the numbers from 1 to a number bigger than 25?

### The Moons of Vuvv

##### Age 7 to 11Challenge Level

The planet of Vuvv has seven moons. Can you work out how long it is between each super-eclipse?

### Multiplication Squares

##### Age 7 to 11Challenge Level

Can you work out the arrangement of the digits in the square so that the given products are correct? The numbers 1 - 9 may be used once and once only.

### Colour in the Square

##### Age 7 to 16Challenge Level

Can you put the 25 coloured tiles into the 5 x 5 square so that no column, no row and no diagonal line have tiles of the same colour in them?

##### Age 11 to 14Challenge Level

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

### Integrated Product Sudoku

##### Age 11 to 16Challenge Level

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.

### Ratio Sudoku 1

##### Age 11 to 16Challenge Level

A Sudoku with clues as ratios.

### Product Sudoku

##### Age 11 to 16Challenge Level

The clues for this Sudoku are the product of the numbers in adjacent squares.

### Diagonal Product Sudoku

##### Age 11 to 16Challenge Level

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

### Ratio Sudoku 3

##### Age 11 to 16Challenge Level

A Sudoku with clues as ratios or fractions.

### Weights

##### Age 11 to 14Challenge Level

Different combinations of the weights available allow you to make different totals. Which totals can you make?

### Mystery Matrix

##### Age 7 to 11Challenge Level

Can you fill in this table square? The numbers 2 -12 were used to generate it with just one number used twice.

### All the Digits

##### Age 7 to 11Challenge Level

This multiplication uses each of the digits 0 - 9 once and once only. Using the information given, can you replace the stars in the calculation with figures?

##### Age 7 to 11Challenge Level

Can you put plus signs in so this is true? 1 2 3 4 5 6 7 8 9 = 99 How many ways can you do it?

### A First Product Sudoku

##### Age 7 to 14Challenge Level

Given the products of adjacent cells, can you complete this Sudoku?

### American Billions

##### Age 11 to 14Challenge Level

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...

### Cinema Problem

##### Age 11 to 14Challenge Level

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

### Pole Star Sudoku 2

##### Age 11 to 16Challenge Level

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

### Zargon Glasses

##### Age 7 to 11Challenge Level

Zumf makes spectacles for the residents of the planet Zargon, who have either 3 eyes or 4 eyes. How many lenses will Zumf need to make all the different orders for 9 families?

### Pouring the Punch Drink

##### Age 7 to 11Challenge Level

There are 4 jugs which hold 9 litres, 7 litres, 4 litres and 2 litres. Find a way to pour 9 litres of drink from one jug to another until you are left with exactly 3 litres in three of the jugs.