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MathXplosion, Ep 32: A mean trick

Video MathXplosion, Ep 32: A mean trick

TLF ID M025010

Learn a cool trick using the concept of the mean (or average). Pick any 3 x 3 block of dates on a monthly calendar. The number in the middle square is the mean of the nine numbers that form the 3 x 3 square. If you add all the numbers and divide the total by nine (the number of squares), the answer is the number in the central position. So to find the sum of the nine numbers quickly, just multiply the number in the middle by 9.

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Educational details

Year level

5

Topics Mean Central tendency Problem solving Division Multiplication Remainders Mental arithmetic Mixed numbers Commutativity Distributivity Associativity Written calculations
Learning area
  • Mathematics

Other details

Contributors
  • Contributor
  • Name: Australian Broadcasting Corporation
  • Organization: Australian Broadcasting Corporation
  • Description: Creator
  • URL: http://www.abc.net.au
  • Name: Education Services Australia
  • Organization: Education Services Australia
  • Description: Data manager
  • Address: VIC, AUSTRALIA
  • URL: http://www.esa.edu.au/
  • Publisher
  • Name: Australian Broadcasting Corporation
  • Organization: Australian Broadcasting Corporation
  • Description: Publisher
  • URL: http://www.abc.net.au
  • Resource metadata contributed by
  • Name: Education Services Australia Ltd
  • Organisation: Education Services Australia Ltd
  • Address: AUSTRALIA
  • URL: www.esa.edu.au
Access profile
  • Generic
Learning Resource Type
  • Video
Rights
  • Metadata © Australian Broadcasting Corporation and Education Services Australia Ltd 2012 (except where otherwise indicated). Digital content © Australian Broadcasting Corporation 2012 (except where otherwise indicated).