Are you good at numbers? Guess the secret number! An efficient way to improve your concentration in a funny way.
After each guess you receive the result consisting in the number of guessed digits in the right position (C) and the number of guessed digits in the wrong position (N)
e.g.
Secret number: 3264
Guessed number: 1234
Result: 2C 1N
(C: 2 and 4, N: 3)