Working systematically

problem

Distinct in a Line

Age

11 to 14

Challenge level

3 out of 3

This grid can be filled so that each of the numbers 1, 2, 3, 4, 5 appears just once in each row, column and diagonal. Which number goes in the centre square?
problem

Almost Constant Digits

Age

11 to 14

Challenge level

3 out of 3

How many 10-digit numbers containing only 1s, 2s and 3s can you write?
problem

Kangaroo Hops

Age

11 to 14

Challenge level

3 out of 3

Weekly Problem 11 - 2011
Kanga hops ten times in one of four directions. At how many different points can he end up?
problem

The Best Card Trick?

Age

11 to 16

Challenge level

1 out of 3

Time for a little mathemagic! Choose any five cards from a pack and show four of them to your partner. How can they work out the fifth?
problem

Diagonal Product Sudoku

Age

11 to 16

Challenge level

1 out of 3

Given the products of diagonally opposite cells - can you complete this Sudoku?
problem

Who's Who?

Age

11 to 16

Challenge level

2 out of 3

Can you solve the clues to find out who's who on the friendship graph?
problem

Logo Challenge - Triangles-Squares-Stars

Age

11 to 16

Challenge level

2 out of 3

Can you recreate these designs? What are the basic units? What movement is required between each unit? Some elegant use of procedures will help - variables not essential.
problem

Logo Challenge - The Logic of Logo

Age

11 to 16

Challenge level

2 out of 3

Just four procedures were used to produce a design. How was it done? Can you be systematic and elegant so that someone can follow your logic?
problem

Star Product Sudoku

Age

11 to 16

Challenge level

2 out of 3

The puzzle can be solved by finding the values of the unknown digits (all indicated by asterisks) in the squares of the $9\times9$ grid.
problem

Olympic Logic

Age

11 to 16

Challenge level

2 out of 3

Can you use your powers of logic and deduction to work out the missing information in these sporty situations?