From nrich.maths.org/2007 and www.cut-the-knot.org/do_you_know/digits.shtml
If you write plus signs between each successive pair of the digits 1 to 9, this is what you get:
1+2+3+4+5+6+7+8+9=45
However, if you alter the placement of the plus signs, you could also get:
12+3+45+6+7+8+9=90
Can you place plus signs below so that the following is true?
1 2 3 4 5 6 7 8 9 = 99
How many ways can you do it?
Can you place plus or minus signs below so that the following is true?
1 2 3 4 5 6 7 8 9 = 100
See if you can get more than one solution.
Except where otherwise noted, content on this site is licensed under a