Addition and subtraction

game

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.
problem

6 by 6 Mathdokus

Age

7 to 16

Challenge level

Can you use the clues to complete these 6 by 6 Mathematical Sudokus?
problem

Eight Dominoes

Age

7 to 16

Challenge level

Using the 8 dominoes, can you make a square where each of the columns and rows adds up to 8?
problem

Calendar Capers

Age

11 to 14

Challenge level

Choose any three by three square of dates on a calendar page...
problem

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 other possibilities for yourself!
problem

Have You Got It?

Age

11 to 14

Challenge level

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

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"?
problem

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.
problem

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?
problem

Calculation 2000

Age

11 to 14

Challenge level

Weekly Problem 49 - 2013
What is the value of 2000 + 1999 × 2000?