The numbers 0-9 are lined up in a row, like this:

0 1 2 3 4 5 6 7 8 9

You have to put in + and - signs in the blanks, so that in the end it will all equal 1.

Also, if possible, try to make expressions resulting in 0 and -1.

There are 23 ways of putting + and - signs in the blanks, such that in the end it will all equal 1.

example 1: 0+1+2+3+4+5-6-7+8-9 = 1
example 2: 0-1-2-3-4-5+6-7+8+9 = 1

There are 23 ways of putting + and - signs in the blanks, such that in the end it will all equal -1.

example 1: 0+1+2+3+4+5-6+7-8-9 = -1
example 2: 0-1-2-3-4-5+6+7-8+9 = -1

There is no way that we can make it add upto 0 or indeed to any even number because in the list of numbers are an odd number of odd numbers (1,3,5,7,&9), hence regardless of the placement of the signs, the full expression will always equal an odd number.

Posted by Sanjay on 2003-05-21 02:23:42