This is the NPR Sunday Puzzle for the week of 1/3/2010. This challenge came from Ed Pegg Jr., who runs http://www.mathpuzzle.com/. Write down the digits from 2 to 7, in order. Add two mathematical symbols to get an expression equaling 2010. What symbols are these? Answer: 2345*6/7=2010 Here are all the solutions for the years from 1 to 5000. ```C:\Users\Lee\MYSTUF~1\tc>tinyc.exe tiny-c/PC Interpreter Version PC-01-07 Copyright (c) 1984 by Scott B. Guthery Implemented 5/16/09 by Lee Bradley / Ed Davis tiny-c Shell - 2/9/9 tc>.r npr.tc 1698 0 48 1698 22802 tc>.npr npr.tc - tct - 1/8/2010 see http://primepuzzle.com/tc/npr.html 23+45-67=1 23-45+67=45 23+45+67=135 234-5-67=162 234-56-7=171 234+5-67=172 234-56+7=185 234-56/7=226 234+56/7=242 2+345-67=280 234+56-7=283 234-5+67=296 234+56+7=297 234+5+67=306 2+345+67=414 23+456-7=472 23+456+7=486 2-34+567=535 234+5*67=569 23-4+567=586 23+4+567=594 2+34+567=603 2*345-67=623 234+56*7=626 2*34+567=635 23*4+567=659 2*345+67=757 23*45-67=968 23*45+67=1102 234*5-67=1103 234*5+67=1237 234*56/7=1872 2345*6/7=2010 23+4*567=2291 2345-6*7=2303 2345-6-7=2332 2345+6-7=2344 2345-6+7=2346 2345+6+7=2358 2345+6*7=2387 23+45*67=3038 23+456*7=3215 2+3456-7=3451 2+3456+7=3465 23*45*67=3809 2-3+4567=4566 2+3+4567=4572 2*3+4567=4573 ``` These were generated by the tiny-c program npr.tc. The tiny-c program was translated into BASIC and may be seen at npr.bas. 1 45 135 162 171 172 185 226 242 280 283 296 297 306 414 472 486 535 569 586 594 603 623 626 635 659 757 968 1102 1103 1237 1872 2010 2291 2303 2332 2344 2346 2358 2387 3038 3215 3451 3465 4566 4572 4573 6905 6919 10481 10495 13097 13111 13703 14063 14077 19280 23117 24194 27402 38556 46230 48384 52164 69345 73416 78390 91728 98490 All 69 positive (see above) (and 160-69=91 negative) values of the (1+2+3+4)*4*4=160 expressions that can be built using the numbers 2 thru 7 in order and +, -,*, / are shown at http://home.astound.net/puzzleblog/2010Expressions.htm Blaine's Puzzle Blog has a discussion of this interesting problem.