A person starts writing all 4 digit numbers .How many times had he written the digit 3?

• 3700
  _ _ _ 3 = 9*10*10
  _ _ 3 _ = 9*10*10
  _ 3 _ _ = 9*10*10
  3 _ _ _ = 10*10*10
  
  900+900+900+1000=3700
  
  
  
• 10 years agoHelpfull: Yes(29) No(7)
• case 1:no of 4 digit nos with one 3 digit=4C1*9*9*9=2916
  case 2:no of 4 digit nos with two 3 digit=4C2*9*9=486
  case3:no of 4 digit nos with three 3 digit=4C3*9=36
  case 4:no of 4 digit nos with one 4 digit=1
  No of times we typed digit 3=(2916*1)+(486*2)+(36*3)+(1*1)=3997(ans)
• 10 years agoHelpfull: Yes(26) No(8)
• Number of 3's at units place(1000 to 9999)=900
  Number of 3's at tenths place(1000 to 9999)=900
  Number of 3's at hundreds place(1000 to 9999)=900
  Number of 3's at thousands place(1000 to 9999)=1000
  
  therefore total number of 3's =(900+900+900+1000)=3700
• 10 years agoHelpfull: Yes(4) No(0)
• case 1:no of 4 digit nos with one 3 digit=4C1*9*9*9=2916
  case 2:no of 4 digit nos with two 3 digit=4C2*9*9=486
  case3:no of 4 digit nos with three 3 digit=4C3*9=36
  case 4:no of 4 digit nos with four 3 digit=4C4=1
  No of times we typed digit 3=(2916*1)+(486*2)+(36*3)+(1*4)=4000(ans)
• 10 years agoHelpfull: Yes(2) No(4)
• 3 is 0-99 is 20
  3 is 100-999 is 100
  3 is 1000-9999 is 1000
  
  ans 1120
• 10 years agoHelpfull: Yes(1) No(11)
• ans is 3699
• 10 years agoHelpfull: Yes(0) No(4)