Minus by One

Minus by 1
Keep our brain working and productive.
Easy math game for kids and family.
Given random four digit integer, e.g. 6591.
Subtract one from each digit, output four new digits, i.e. 5480.
Think and type it as fast as you can in 60 seconds.
Get as many as correct answers.
Correct answer, earn +1 point.
Incorrect answer, deduct -1 point.
Brain, eyes and finger productivity.

Leaderboard is given by the Game Center.
First time play, login to Game Center first.
Best score is stored in Game Center along with other players.

Add by 1
Include Add by one and leaderboard.
Given random four digit integer, e.g. 6591.
Add one from each digit, output four new digits, i.e. 7602.
Think and type it as fast as you can in 60 seconds.
Get as many as correct answers.
Correct answer, earn +1 point.
Incorrect answer, deduct -1 point.
Brain, eyes and finger productivity.
Leaderboard is given by the Game Center.