Monday, August 06, 2007
An Arithmetic Puzzle

Okay, so I go to write a post today and find I have some good longer posts but didn't feel like putting one of those together today. And unfortunately, I struggled to come up with a short topic :) To the few readers I have at the moment, I'll instead post a little puzzle that one of my smartest friends shared with me. It's the type of thing you see right away or get stuck for awhile, I think.

In this equation: 101 - 102 = 1

Move one and only one digit to make this equation true. By "one digit" I mean literally one digit - not one "type" of digit - so you can't move more than one 1 for example.

Enjoy

Monday, August 06, 2007 10:22:38 PM (Eastern Standard Time, UTC-05:00)  #    Comments [2]  |  Trackback
Tuesday, August 07, 2007 9:41:05 AM (Eastern Standard Time, UTC-05:00)
I don't understand how to "move" a digit.

A. What happens to the remaining digits when I extract the one I wish to move?
- Do they get zeroed out? (take the 2 from 102, leaving 100)
- Do they shift right? (take the 2 from 102, leaving 10)
- Does it swap with the digit in the location I wish to move it to? (take the 2 from 102, swap it with the right-hand 1 in 101, leaving 102 - 101; this would be the simplest solution, but it seems like this would be moving two digits, and the problem states that we can only move one)
B. What happens when I put the extracted digit into its new location?
- Does it behave like a string insertion? (insert the 2 taken from 102 before the 0 in 101, making 1201)
- Does the extracted digit maintain the sign of the number it's taken from? (take the 2 from -102, and use it as -2)
- Does it need to adhere to arithmetic rules? (take the 1 from the right-hand side of the equation, turning it negative when it crosses over to the left-hand side)

More constraints, please!
spugbrap
Friday, September 07, 2007 2:34:55 PM (Eastern Standard Time, UTC-05:00)
I assume the answer is to move the 2 such that it's 10 squared?
Michael
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