Hooked on Sudoku

A little over a year ago, my dad mentioned a game called Sudoku and said that it was really fun. I didn't have time then to try it out but I was bored the other day and decided to find some trivia and mind games. I ran across Sudoku on Braingle and have become hooked. If you've never heard of it before, there is a grid 9x9 and the object is to fill all the cells with numbers 1-9 such that each row, column and 3x3 sub-grid only has one occurence of each number. It's amazingly addictive. Plus it's like a workout for the mind. Gotta keep that muscle in shape.