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### Number and algebra

### Geometry and measure

### Probability and statistics

### Working mathematically

### For younger learners

### Advanced mathematics

# Number Operations & Calculation Methods

### Countdown

### Consecutive Numbers

### The Remainders Game

### Method in Multiplying Madness?

### Two and Two

### Magic Letters

### Consecutive Seven

### Keep it Simple

### Number Daisy

### Can You Make 100?

### Strange Bank Account

### Fractions Jigsaw

### Up, Down, Flying Around

### Going Round in Circles

### Adding and Subtracting Positive and Negative Numbers

### Round and Round and Round

### Missing Multipliers

### Have You Got It?

### Twisting and Turning

### Where Can We Visit?

### Impossibilities

### More Twisting and Turning

### Overlaps

### Connect Three

### Egyptian Fractions

### Remainders

### Weights

### The Greedy Algorithm

### Consecutive Negative Numbers

### Largest Product

### Cinema Problem

### Almost One

### Number Operations and Calculation Methods - Short Problems

### 5 by 5 Mathdokus

### Same Answer

### Countdown Fractions

Y*ou may also be interested in this collection of activities from the STEM Learning website, that complement the NRICH activities above.*

Links to the University of Cambridge website
Links to the NRICH website Home page

Nurturing young mathematicians: teacher webinars

30 April (Primary), 1 May (Secondary)

30 April (Primary), 1 May (Secondary)

Or search by topic

Age 7 to 14

Challenge Level

Here is a chance to play a version of the classic Countdown Game.

Age 7 to 14

Challenge Level

An investigation involving adding and subtracting sets of consecutive numbers. Lots to find out, lots to explore.

Age 7 to 14

Challenge Level

Play this game and see if you can figure out the computer's chosen number.

Age 7 to 14

Challenge Level

Watch our videos of multiplication methods that you may not have met before. Can you make sense of them?

Age 7 to 16

Challenge Level

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

Age 11 to 14

Challenge Level

Charlie has made a Magic V. Can you use his example to make some more? And how about Magic Ls, Ns and Ws?

Age 11 to 14

Challenge Level

Can you arrange these numbers into 7 subsets, each of three numbers, so that when the numbers in each are added together, they make seven consecutive numbers?

Age 11 to 14

Challenge Level

Can all unit fractions be written as the sum of two unit fractions?

Age 11 to 14

Challenge 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?

Age 11 to 14

Challenge Level

How many ways can you find to put in operation signs (+, −, ×, ÷) to make 100?

Age 11 to 14

Challenge Level

Imagine a very strange bank account where you are only allowed to do two things...

Age 11 to 14

Challenge Level

A jigsaw where pieces only go together if the fractions are equivalent.

Age 11 to 14

Challenge Level

Play this game to learn about adding and subtracting positive and negative numbers

Age 11 to 14

Challenge Level

Mathematicians are always looking for efficient methods for solving problems. How efficient can you be?

Age 11 to 14

How can we help students make sense of addition and subtraction of negative numbers?

Age 11 to 14

Challenge Level

Where will the point stop after it has turned through 30 000 degrees? I took out my calculator and typed 30 000 ÷ 360. How did this help?

Age 7 to 14

Challenge Level

What is the smallest number of answers you need to reveal in order to work out the missing headers?

Age 11 to 14

Challenge Level

Can you explain the strategy for winning this game with any target?

Age 11 to 14

Challenge Level

Take a look at the video and try to find a sequence of moves that will untangle the ropes.

Age 11 to 14

Challenge 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?

Age 11 to 14

Challenge Level

Just because a problem is impossible doesn't mean it's difficult...

Age 11 to 16

Challenge Level

It would be nice to have a strategy for disentangling any tangled ropes...

Age 11 to 14

Challenge Level

Can you find ways to put numbers in the overlaps so the rings have equal totals?

Age 11 to 16

Challenge Level

In this game the winner is the first to complete a row of three. Are some squares easier to land on than others?

Age 11 to 14

Challenge Level

The Egyptians expressed all fractions as the sum of different unit fractions. Here is a chance to explore how they could have written different fractions.

Age 7 to 14

Challenge Level

I'm thinking of a number. My number is both a multiple of 5 and a multiple of 6. What could my number be?

Age 11 to 14

Challenge Level

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

Age 11 to 14

Challenge Level

The Egyptians expressed all fractions as the sum of different unit fractions. The Greedy Algorithm might provide us with an efficient way of doing this.

Age 11 to 14

Challenge Level

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

Age 11 to 14

Challenge Level

Which set of numbers that add to 100 have the largest product?

Age 11 to 14

Challenge Level

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.

Age 11 to 14

Challenge Level

Choose some fractions and add them together. Can you get close to 1?

Age 11 to 16

A collection of short problems on number operations and calculation methods.

Age 7 to 16

Challenge Level

Can you use the clues to complete these 5 by 5 Mathematical Sudokus?

Age 11 to 14

Challenge Level

Aisha's division and subtraction calculations both gave the same answer! Can you find some more examples?

Age 11 to 16

Challenge Level

Here is a chance to play a fractions version of the classic Countdown Game.

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