Twin-Cards app for iPhone and iPad
Make a pair of identical cards using add / minus / multiply / divide / glue.
With more digits that number becomes, a higher score the player will get rewarded:
1 digit: 100 points
2 digits: 100 points
3 digits: 300 points
4 digits: 700 points
5 digits: 1500 points (guess how)
The player can opt to play for 3 / 5 / 10 minutes and earn as much score as possible. They can also compete with their friends by typing in the same seeds (in the text box on the menu), so that all players get exactly the same cards.