document.write( "Question 1172321: The integers 1, 2, 3, ...., 40 are written on white board. An operation is then repeated 39 times. In each repetition any two numbers say a and b currently on white board are erased and new number a + b -1 is written. What will be the number left on white board at the end? \n" ); document.write( "
Algebra.Com's Answer #797325 by ikleyn(52795)\"\" \"About 
You can put this solution on YOUR website!
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\n" ); document.write( "\n" ); document.write( "            Edwin provided a brilliant starting idea in his post.\r
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\n" ); document.write( "\n" ); document.write( "            I came to complete/(to fix)  his solution accurately.\r
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\n" ); document.write( "\n" ); document.write( "If the operation was repeated  39  times,  then the  SINGLE  number which left on the board,  is  820 - 39.\r
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\n" ); document.write( "\n" ); document.write( "After the  39-th step/operation,  there is  NOTHING  to do;  the algorithm does not work further,
\n" ); document.write( "and the  40-th step can not be done  (and is not assumed to be done).\r
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\n" ); document.write( "\n" ); document.write( "So,  the final number is   820-39 = 781.         ANSWER\r
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