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MathXplosion, Ep 32: A mean trick

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Man sits on floor with giant calculator
MathXplosion, Ep 32: A mean trick

SUBJECTS:  Maths

YEARS:  5–6


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.


Acknowledgements

Video © GAPC Entertainment.


Date of broadcast: 22 Oct 2018


Copyright

Metadata © Australian Broadcasting Corporation and Education Services Australia Ltd 2012 (except where otherwise indicated). Digital content © Australian Broadcasting Corporation (except where otherwise indicated). Video © Australian Broadcasting Corporation (except where otherwise indicated). All images copyright their respective owners. Text © Australian Broadcasting Corporation and Education Services Australia is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License (CC BY-SA 4.0).

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