Guess 4 digit number discussion

Guess 4 digit number discussion

Please try to ask minimum number of questions to identify a four-digit number. 
For example, guess 1111, 
let 1111 -> 1 number is correct , 1 number at correct position
    2111 -> 2q number is correct , 0 number at correct position
    
Analysis of the problem:        
      4 digits, 4 position 
      10^4 * 4 * 3 * 2 * 1
      minimum questions I should ask 24 choices
      0 - 9 10 -> one digit - 4 distinct 
      taking 10, give digits 4 digit , 10 times - 9 times
      2 digits
      3 digits
      4 digits
      identify -> 
      
      10 times -> at time 
      four digits - at most -> 0, 1, 2, ,
      1, 2, -> add new digit <-