Number Operations & Calculation Methods

This is part of our Secondary Curriculum collection of favourite rich tasks arranged by topic.

Countdown

Age 7 to 14Challenge Level

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

Consecutive Numbers

Age 7 to 14Challenge Level

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

The Remainders Game

Age 7 to 14Challenge Level

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

Age 7 to 14Challenge Level

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

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.

Magic Letters

Age 11 to 14Challenge Level

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

Consecutive Seven

Age 11 to 14Challenge 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?

Keep it Simple

Age 11 to 14Challenge Level

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

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?

Can You Make 100?

Age 11 to 14Challenge Level

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

Strange Bank Account

Age 11 to 14Challenge Level

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

Fractions Jigsaw

Age 11 to 14Challenge Level

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

Up, Down, Flying Around

Age 11 to 14Challenge Level

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

Going Round in Circles

Age 11 to 14Challenge Level

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

Adding and Subtracting Positive and Negative Numbers

Age 11 to 14

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

Making a Difference

Age 11 to 14Challenge Level

How many different differences can you make?

Round and Round and Round

Age 11 to 14Challenge 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?

Missing Multipliers

Age 7 to 14Challenge Level

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

Have You Got It?

Age 11 to 14Challenge Level

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

Cryptarithms

Age 11 to 14Challenge Level

Can you crack these cryptarithms?

Twisting and Turning

Age 11 to 14Challenge Level

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

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?

Impossibilities

Age 11 to 14Challenge Level

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

More Twisting and Turning

Age 11 to 16Challenge Level

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

Overlaps

Age 11 to 14Challenge Level

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

Connect Three

Age 11 to 16Challenge Level

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

Egyptian Fractions

Age 11 to 14Challenge 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.

Remainders

Age 7 to 14Challenge 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?

Weights

Age 11 to 14Challenge Level

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

The Greedy Algorithm

Age 11 to 14Challenge 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.

Consecutive Negative Numbers

Age 11 to 14Challenge Level

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

Largest Product

Age 11 to 14Challenge Level

Which set of numbers that add to 10 have the largest product?

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.

Almost One

Age 11 to 14Challenge Level

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

The Root of the Problem

Age 14 to 18Challenge Level

Find the sum of this series of surds.

Number Operations and Calculation Methods - Short Problems

Age 11 to 16

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

5 by 5 Mathdokus

Age 7 to 16Challenge Level

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

Age 11 to 14Challenge Level

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

Countdown Fractions

Age 11 to 16Challenge Level

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

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