Celebrate 25 Years of NRICH

Age
5 to 14
Exploring and noticing Working systematically Conjecturing and generalising Visualising and representing Reasoning, convincing and proving
Being curious Being resourceful Being resilient Being collaborative

To celebrate NRICH's 25th birthday, we have created a special version of one of our favourite games, Got It.

Got It is a game for two players.

The challenge is to be the first player to hit the target of 25 (as a celebration of NRICH's birthday!).

  • You can play against the computer or with a friend. 
  • The first player chooses a whole number from 1 to 5.
  • The second player chooses a whole number from 1 to 5, which is added onto the first player's number to make a new total.
  • Play continues in this way, with players taking turns to add a whole number from 1 to 5 to the running total.
  • The winner is the player who reaches the target of 25.

Play the game several times.

  • Can you find a winning strategy?
  • Can you always win?

Does your strategy depend on whether or not you go first?

To change the game, choose a new Got It target or a new range of numbers to add on.

Test out the strategy you found earlier. Does it need adapting?

  • Can you work out a winning strategy for any target?
  • Can you work out a winning strategy for any range of numbers?
  • Is it best to start the game? Always?

Away from the computer, challenge your friends:

One of you names the target and range and lets the other player start.

Extensions:

  • Can you play without writing anything down?
  • Consider playing the game where a player CANNOT add the same number as that used previously by the opponent.