Other tags that relate to 2-digit Square
Generalising. Integers. Place value. Expanding and factorising quadratics. Addition & subtraction. Factors and multiples. Divisibility. Mathematical reasoning & proof. Creating and manipulating expressions and formulae. Difference of two squares.There are 73 results
Broad Topics > Calculations and Numerical Methods > Addition & subtraction
Double Digit
Age 11 to 14
Challenge Level
Choose two digits and arrange them to make two double-digit numbers. Now add your double-digit numbers. Now add your single digit numbers. Divide your double-digit answer by your single-digit answer. . . .
Arrange the Digits
Age 11 to 14
Challenge Level
Can you arrange the digits 1,2,3,4,5,6,7,8,9 into three 3-digit numbers such that their total is close to 1500?
As Easy as 1,2,3
Age 11 to 14
Challenge Level
When I type a sequence of letters my calculator gives the product of all the numbers in the corresponding memories. What numbers should I store so that when I type 'ONE' it returns 1, and when I type. . . .
The Patent Solution
Age 11 to 14
Challenge Level
A combination mechanism for a safe comprises thirty-two tumblers numbered from one to thirty-two in such a way that the numbers in each wheel total 132... Could you open the safe?
Aba
Age 11 to 14
Challenge Level
In the following sum the letters A, B, C, D, E and F stand for six distinct digits. Find all the ways of replacing the letters with digits so that the arithmetic is correct.
Tis Unique
Age 11 to 14
Challenge Level
This addition sum uses all ten digits 0, 1, 2...9 exactly once. Find the sum and show that the one you give is the only possibility.
Digit Sum
Age 14 to 16 Short
Challenge Level
What is the sum of all the digits in all the integers from one to one million?
Adding All Nine
Age 11 to 14
Challenge Level
Make a set of numbers that use all the digits from 1 to 9, once and once only. Add them up. The result is divisible by 9. Add each of the digits in the new number. What is their sum? Now try some. . . .
Subtraction Surprise
Age 7 to 14
Challenge Level
Try out some calculations. Are you surprised by the results?
Forwards Add Backwards
Age 11 to 14
Challenge Level
What happens when you add a three digit number to its reverse?
Number Pyramids
Age 11 to 14
Challenge Level
Try entering different sets of numbers in the number pyramids. How does the total at the top change?
Two and Two
Age 11 to 16
Challenge Level
How many solutions can you find to this sum? Each of the different letters stands for a different number.
Diagonal Sums
Age 7 to 14
Challenge Level
In this 100 square, look at the green square which contains the numbers 2, 3, 12 and 13. What is the sum of the numbers that are diagonally opposite each other? What do you notice?
Cayley
Age 11 to 14
Challenge 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"?
Crossed Ends
Age 11 to 14
Challenge Level
Crosses can be drawn on number grids of various sizes. What do you notice when you add opposite ends?
Pairs
Age 11 to 14
Challenge Level
Ann thought of 5 numbers and told Bob all the sums that could be made by adding the numbers in pairs. The list of sums is 6, 7, 8, 8, 9, 9, 10,10, 11, 12. Help Bob to find out which numbers Ann was. . . .
Alphabet Soup
Age 11 to 14
Challenge Level
This challenge is to make up YOUR OWN alphanumeric. Each letter represents a digit and where the same letter appears more than once it must represent the same digit each time.
Magic Squares for Special Occasions
Age 11 to 16
This article explains how to make your own magic square to mark a special occasion with the special date of your choice on the top line.
Score
Age 11 to 14
Challenge Level
There are exactly 3 ways to add 4 odd numbers to get 10. Find all the ways of adding 8 odd numbers to get 20. To be sure of getting all the solutions you will need to be systematic. What about. . . .
Postage
Age 14 to 16
Challenge Level
The country Sixtania prints postage stamps with only three values 6 lucres, 10 lucres and 15 lucres (where the currency is in lucres).Which values cannot be made up with combinations of these postage. . . .
Have You Got It?
Age 11 to 14
Challenge Level
Can you explain the strategy for winning this game with any target?
Got it for Two
Age 7 to 14
Challenge Level
Got It game for an adult and child. How can you play so that you know you will always win?
Football Sum
Age 11 to 14
Challenge Level
Find the values of the nine letters in the sum: FOOT + BALL = GAME
Multiply the Addition Square
Age 11 to 14
Challenge 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?
Add to 200
Age 11 to 14
Challenge Level
By selecting digits for an addition grid, what targets can you make?
Magic Letters
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?
Making Sense of Positives and Negatives
Age 11 to 14
This article suggests some ways of making sense of calculations involving positive and negative numbers.
Can You Make 100?
Age 11 to 14
Challenge Level
How many ways can you find to put in operation signs (+ - x รท) to make 100?
Nice or Nasty for Two
Age 7 to 14
Challenge Level
Some Games That May Be Nice or Nasty for an adult and child. Use your knowledge of place value to beat your opponent.
Up, Down, Flying Around
Age 11 to 14
Challenge Level
Play this game to learn about adding and subtracting positive and negative numbers
And So on and So On
Age 11 to 14
Challenge Level
If you wrote all the possible four digit numbers made by using each of the digits 2, 4, 5, 7 once, what would they add up to?
Nice or Nasty
Age 7 to 14
Challenge Level
There are nasty versions of this dice game but we'll start with the nice ones...
Jugs of Wine
Age 11 to 14
Challenge Level
You have four jugs of 9, 7, 4 and 2 litres capacity. The 9 litre jug is full of wine, the others are empty. Can you divide the wine into three equal quantities?
Consecutive Negative Numbers
Age 11 to 14
Challenge Level
Do you notice anything about the solutions when you add and/or subtract consecutive negative numbers?
Calendar Capers
Age 11 to 14
Challenge Level
Choose any three by three square of dates on a calendar page...
Largest Number
Age 11 to 14
Challenge Level
What is the largest number you can make using the three digits 2, 3 and 4 in any way you like, using any operations you like? You can only use each digit once.
Summing Consecutive Numbers
Age 11 to 14
Challenge 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?
3388
Age 11 to 14
Challenge Level
Using some or all of the operations of addition, subtraction, multiplication and division and using the digits 3, 3, 8 and 8 each once and only once make an expression equal to 24.
Eight Dominoes
Age 7 to 16
Challenge Level
Using the 8 dominoes make a square where each of the columns and rows adds up to 8
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?
Alphabetti Sudoku
Age 11 to 16
Challenge Level
This Sudoku requires you to do some working backwards before working forwards.
Cunning Card Trick
Age 11 to 14
Challenge Level
Delight your friends with this cunning trick! Can you explain how it works?
Cubes Within Cubes
Age 7 to 14
Challenge Level
We start with one yellow cube and build around it to make a 3x3x3 cube with red cubes. Then we build around that red cube with blue cubes and so on. How many cubes of each colour have we used?
Pair Sums
Age 11 to 14
Challenge Level
Five numbers added together in pairs produce: 0, 2, 4, 4, 6, 8, 9, 11, 13, 15 What are the five numbers?
Twenty20
Age 7 to 16
Challenge Level
Fancy a game of cricket? Here is a mathematical version you can play indoors without breaking any windows.
NRICH is part of the family of activities in the Millennium Mathematics Project.