Number Operations & Calculation Methods
Countdown
Here is a chance to play a version of the classic Countdown Game.
Consecutive Numbers
An investigation involving adding and subtracting sets of consecutive numbers. Lots to find out, lots to explore.
The Remainders Game
Play this game and see if you can figure out the computer's chosen number.
Method in Multiplying Madness?
Watch our videos of multiplication methods that you may not have met before. Can you make sense of them?
Two and Two
How many solutions can you find to this sum? Each of the different letters stands for a different number.
Magic Letters
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
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
Can all unit fractions be written as the sum of two unit fractions?
Number Daisy
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?
How many ways can you find to put in operation signs (+, −, ×, ÷) to make 100?
Strange Bank Account
Imagine a very strange bank account where you are only allowed to do two things...
Fractions Jigsaw
A jigsaw where pieces only go together if the fractions are equivalent.
Up, Down, Flying Around
Play this game to learn about adding and subtracting positive and negative numbers
Going Round in Circles
Mathematicians are always looking for efficient methods for solving problems. How efficient can you be?
Adding and Subtracting Positive and Negative Numbers
How can we help students make sense of addition and subtraction of negative numbers?
Round and Round and Round
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
What is the smallest number of answers you need to reveal in order to work out the missing headers?
Have You Got It?
Can you explain the strategy for winning this game with any target?
Twisting and Turning
Take a look at the video and try to find a sequence of moves that will untangle the ropes.
Where Can We Visit?
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
Just because a problem is impossible doesn't mean it's difficult...
More Twisting and Turning
It would be nice to have a strategy for disentangling any tangled ropes...
Overlaps
Can you find ways to put numbers in the overlaps so the rings have equal totals?
Connect Three
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
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
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
Different combinations of the weights available allow you to make different totals. Which totals can you make?
The Greedy Algorithm
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
Do you notice anything about the solutions when you add and/or subtract consecutive negative numbers?
Largest Product
Which set of numbers that add to 100 have the largest product?
Cinema Problem
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.
Almost One
Choose some fractions and add them together. Can you get close to 1?
Number Operations and Calculation Methods - Short Problems
A collection of short problems on number operations and calculation methods.
5 by 5 Mathdokus
Can you use the clues to complete these 5 by 5 Mathematical Sudokus?
Same Answer
Aisha's division and subtraction calculations both gave the same answer! Can you find some more examples?
Countdown Fractions
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.