median
don steward
mathematics teaching 10 ~ 16

Tuesday, 7 December 2010

Zorro using 1 to 7

use digits1 to 7 (once only) so that the lines of three have the same total



what totals are possible and how many variants are there? 

prove that the middle must be even

prove that 7 and 6 must not be in the same line









ignoring unimportant swaps, show that there are: 

  • two solutions with 2 in the middle
  • three with 4 in the middle 
  • two with 6 in the middle

prove that only totals of 11, 12 and 13 are possible

why is a total of 14 impossible?





















this is the same as a task called 'Haitch'
Graeme Brown produced an Excel interactive version to download for nrich here



                                                                                                                               

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