For those people who like Maths puzzles, have you tried Kakuro yet?
Kakuro is like a crossword puzzle with numbers. Each “word” must add up to the number provided in the clue above it or to the left. Words can only use the numbers 1 through 9, and a given number can only be used once in a word. Every Kakuro puzzle has one and only solution, and can be solved through logic alone.
There are some online puzzles to try at http://www.kakuroconquest.com/
We suggest you try the easy level. You can check your progress at every stage by pressing the check button (if they come up red, those are the mistakes)