Combinations

problem
Favourite

Crossing the Bridge

Age

11 to 18

Challenge level

Four friends must cross a bridge. How can they all cross it in just 17 minutes?
problem
Favourite

Chances Are

Age

14 to 16

Challenge level

Which of these games would you play to give yourself the best possible chance of winning a prize?
problem
Favourite

Teams

Age

16 to 18

Challenge level

Two brothers belong to a club with 10 members. Four are selected for a match. Find the probability that both brothers are selected.
problem

Lesser Digits

Age

11 to 14

Challenge level

How many positive integers less than or equal to 4000 can be written down without using the digits 7, 8 or 9?
problem

Sam Again

Age

11 to 14

Challenge level

Here is a collection of puzzles about Sam's shop sent in by club members. Perhaps you can make up more puzzles, find formulas or find general methods.
problem

Patchwork Quilt

Age

7 to 14

Challenge level

Squares of the type shown are sewn together to make a quilt. How many different quilts can be made?
problem

Cereal Packets

Age

7 to 11

Challenge level

How can you put five cereal packets together to make different shapes if you must put them face-to-face?
problem

Flagging

Age

11 to 14

Challenge level

How many tricolour flags are possible with 5 available colours such that two adjacent stripes must NOT be the same colour. What about 256 colours?
problem

Semaphore Signals

Age

7 to 11

Challenge level

Semaphore is a way to signal the alphabet using two flags. You might want to send a message that contains more than just letters. How many other symbols could you send using this code?
problem

Brailler

Age

11 to 14

Challenge level

The machine I use to produce Braille messages is faulty and one of the pins that makes a raised dot is not working. I typed a short message in Braille. Can you work out what it really says?