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NPR Sunday Puzzle Challenge

February 21, 2007

NPR Sunday Puzzle Challenge for February 18 is reminiscent of the 2007 puzzle that several of us worked on over at Let’s Play Math. You have to create nine different mathematical expressions that equal eight, using the digits 2, 7 and a third digit that is 1 for the first expression, 2 for the second, etc… You can use plus, minus, times, divided by, exponents and decimal points, plus parentheses as needed. You must use each of the three digits exactly once. (The challenge is credited to Robert Waynewright in New Rochelle, N.Y.)

This one ends Thursday, sometime before 3. I’ve managed to get all of them but 8 (that is, form 8 from the digits 2, 7 and 8, and the allowed operations) so far.

2 Comments leave one →
  1. February 22, 2007 9:03 am

    Sounds interesting. I’ve got five of the answers right off the top of my head (#5 is thanks to your reminder about decimals in the 2007 game), but I’ll have to find some spare time later today to think about the others.

  2. February 22, 2007 9:31 pm

    I’m stumped by #7. Got all the others.

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