A person writing all 4 digit number. How many times he will use 2?

• if select any no. from 0-9 the probability of each digit=1/10,consider no. be wxyz
  probability of 2 at w=1/9
  prob. of 2 at x=1/10
  prob. of 2 at y=1/10
  prob. of 2 at z=1/10
  so, 1/9+1/10+1/10+1/10=37/90
  total no. of 4 digit no. = 9*10*10*10=9000
  so, totalno. of 2=(37*9000)/90=3700
• 9 years agoHelpfull: Yes(24) No(2)
• ans:3700
  at 1's place=900 times
  at 10's place=900 times
  at 100's place=900 times
  at 1000's place(from 2000 to 2999)=1000 times
  total=1000+900+900+900=3700
  
• 9 years agoHelpfull: Yes(11) No(3)
• total no. of four digit numbers is 9000
  no of digits that does not contain 2 is
  thousands place can be filled in 8 ways
  hundreds place can be filled in 9 ways
  ten's place in 9 ways
  units place in 9 ways
  8*9*9*9=5832
  now no of digits that contain 2 is 9000-5832=3168
• 9 years agoHelpfull: Yes(5) No(0)
• 3700 time we use 2 to write all 4 digit number.
  at the unit place 2 comes 900 times
  at the tenth place 2 comes 900 times
  at the hundred th place 2 comes 900 times
  at the last thousend th place 2 will comes 1000 time so
  that 900*3+1000=3700 is the final answer..!!!
  
• 9 years agoHelpfull: Yes(3) No(1)
• 1133 is the answer
  
• 9 years agoHelpfull: Yes(2) No(5)
• 3811 ways.....we can use two 2s also and three 2s too......consider that way too
• 9 years agoHelpfull: Yes(0) No(2)