Working systematically

Your challenge is to find the longest way through the network following this rule. You can start and finish anywhere, and with any shape, as long as you follow the correct order.

This problem is based on a code using two different prime numbers less than 10. You'll need to multiply them together and shift the alphabet forwards by the result. Can you decipher the code?

Complete the magic square using the numbers 1 to 25 once each. Each row, column and diagonal adds up to 65.

This sudoku requires you to have "double vision" - two Sudoku's for the price of one

Imagine a stack of numbered cards with one on top. Discard the top, put the next card to the bottom and repeat continuously. Can you predict the last card?

Solve the equations to identify the clue numbers in this Sudoku problem.

In how many ways can you give change for a ten pence piece?

Use the clues about the shaded areas to help solve this sudoku

Tina has chosen a number and has noticed something about its factors. What number could she have chosen? Are there multiple possibilities?

Use cunning to work out a strategy to win this game.