This is a game for two players. Let's call them A and B.

A begins by typing any number into a calculator.

B then multiplies this number by another number, trying to get the answer as close as possible to 100.

A then multiplies this number by another number, trying to get even closer to 100.

The winner is the first player to make the total equal a hundred point something.

Play the game many times. Can you find a good strategy for winning?



A Transum Maths Starter Of The Day


Topics: Starter | Arithmetic | Calculator | Decimals | Estimating | Games

  • Nikki, Devon
  • Excellent. A great reminder for kids who have just been investigating what happens when you multiply or divide a number by a value between 0 and 1. Thanks
  • Transum,
  • This is starter for two students working together. There is a lot to be gained from pupils collaborating on problem solving as they not only learn from their partner but also benefit from practising putting their thoughts into words so their partner can follow their line of reasoning. Technically this starter puts one pupil in competition against the other but all of the other Starters of the Day can be presented in a 'working together' format either in pairs or small groups.
  • Matthew Zhao, 4AD, Craigslea State School
  • A great mental teaser to let me think about a great way of a never-ending game. Just simply have Player A enter 0 into the calculator, then nobody can ever win because 0x(any number) will always be 0!

How did you use this starter? Can you suggest how teachers could present or develop this resource? Do you have any comments? It is always useful to receive feedback and helps make this free resource even more useful for Maths teachers anywhere in the world.
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Laptops In Lessons

Teacher, do your students have access to computers such as tablets, iPads or Laptops?  This page was really designed for projection on a whiteboard but if you really want the students to have access to it here is a concise URL for a version of this page without the comments:

However it would be better to assign one of the student interactive activities below.

Laptops In Lessons

Here is the URL which will take them to a similar number puzzle.

Student Activity


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