Counting

problem
Favourite

How Odd

Age

5 to 11

Challenge level

This problem challenges you to find out how many odd numbers there are between pairs of numbers. Can you find a pair of numbers that has four odds between them?
problem
Favourite

Which Is Quicker?

Age

7 to 11

Challenge level

Which is quicker, counting up to 30 in ones or counting up to 300 in tens? Why?
problem
Favourite

More Tug of War

Age

7 to 11

Challenge level

In this game, you can add, subtract, multiply or divide the numbers on the dice. Which will you do so that you get to the end of the number line first?
problem
Favourite

Sea Level

Age

7 to 11

Challenge level

What numbers would you put on this number line as it goes under the sea level?
problem
Favourite

Sorting the Numbers

Age

7 to 11

Challenge level

Can you put the numbers in the correct place in this Carroll diagram?
problem
Favourite

Neighbours

Age

7 to 11

Challenge level

In a square in which the houses are evenly spaced, numbers 3 and 10 are opposite each other. What is the smallest and what is the largest possible number of houses in the square?
problem
Favourite

Counting Cards

Age

7 to 11

Challenge level

A magician took a suit of thirteen cards and held them in his hand face down. Every card he revealed had the same value as the one he had just finished spelling. How did this work?
problem
Favourite

Diagonal Sums Sudoku

Age

7 to 16

Challenge level

Solve this Sudoku puzzle whose clues are in the form of sums of the numbers which should appear in diagonal opposite cells.
problem
Favourite

Amazing Card Trick

Age

11 to 14

Challenge level

How is it possible to predict the card?
problem

Doodles

Age

14 to 16

Challenge level

Draw a 'doodle' - a closed intersecting curve drawn without taking pencil from paper. What can you prove about the intersections?