superprismatic 11 Posted July 25, 2010 Report Share Posted July 25, 2010 This problem is about Reverse Polish Notation (RPN) which is explained at http://en.wikipedia.org/wiki/Reverse_Polish_notation. Using RPN with operators chosen from the set {+,-,×,÷}, what is the smallest positive integer which cannot be made from the string of digits 123456789 (in that order) with eight operators interspersed to make a well-formed RPN expression? As an RPN example, the string 12+3+4+5+6+7+8+9 evaluates to 45, 123456789++++++++ evaluates to 45, 1234+-5/67××-89++ evaluates to 60, and 123456789-+-+-+-+ evaluates to 1. Quote Link to post Share on other sites

0 Guest Posted July 25, 2010 Report Share Posted July 25, 2010 This RPN is too complicated to me By the way, the link you posted is misspelled. You need to remove the dot in the end. Quote Link to post Share on other sites

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## superprismatic 11

This problem is about Reverse Polish Notation (RPN) which is explained at http://en.wikipedia.org/wiki/Reverse_Polish_notation.

Using RPN with operators chosen from the set {+,-,×,÷}, what is the smallest positive integer

which

cannotbe made from the string of digits 123456789 (in that order) with eight operatorsinterspersed to make a well-formed RPN expression?

As an RPN example, the string 12+3+4+5+6+7+8+9 evaluates to 45, 123456789++++++++ evaluates to 45,

1234+-5/67××-89++ evaluates to 60, and 123456789-+-+-+-+ evaluates to 1.

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