The Lucky Pirate is a casual mobile game with quite a bit of strategy. Collect items and combine them in the right way to generate coins. Spend coins on new items but make sure you have enough left over to win. It's availabe for both Android and iOS, so you should check it out!
Puzzle Board is a mobile app for iOS and Android. It contains a lot of number puzzles and you can even submit your own puzzles. It's free and not making any money. Sadly Apple charges developers a lot, so at the moment updates are only availble for Android.