Fun math puzzles for kids I'm trying to find fun puzzles for younger people (7 years of age and up). I've browsed the internet, searched through math books etc but haven't really found a stellar puzzle. 
I realize that perhaps math does not lend itself to puzzles that well, since math is very logical, but maybe you can correct me. 
Here are a few "puzzles" I have:


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*I present a matrix of numbers (3x3). The solution is to sum each row and each column. And then to sum the summed rown and summed column. It's not very fun. 

*I present a number, say 4, and two number properties (for example Even and Odd) and also "Neither" and "Both". This is challenging if it is on time. 

*I present a matrix (5x5) of numbers. In this matrix there is a guaranteed sum of 100 "hiding". The total sum of all numbers are often above 1000 (it's not important). The goal is to strike out all numbers, leaving exactly 100. It's not brilliant but it's ok. 


I have looked at hyper cubes, Magic Squares (far too difficult), textual problems etc. Sudoku is perhaps a superb example of a good math game (but also too hard for kids)
Maybe this question is unclear but I would love to hear anything you have to say or if you have any good book/link you can recommend. 

A book I really loved was "The Colossal Book of Short Puzzles and Problems" by Martin Gardner. While I myself couldn't solve about a quarter of the math problems, some of them are easy and simple enough for kids to comprehend and solve, and about half of them have to do with numbers. Even the ones that don't are very intriguing.
