A person starts writing all 3 digits numbers. How many times had he written the digit 2

• when 2 at unit place, then no formed= 90;
  when 2 at tens place, then no formed= 90;
  when 2 at hundreds place, then no formed= 100;
  total= 90+90+100= 280
• 11 years agoHelpfull: Yes(36) No(4)
• 280 times,
  when 2 is at unit place then hundred and tens can be arranged in 9*10=90
  when 2 is at tens place then hundred and tens can be arranged in 9*10=90
  when 2 is at hundred place then tens and unit can be arranged in 10*10=100
  so total is 280 ways
  
• 11 years agoHelpfull: Yes(13) No(0)
• from 1 to 100 each digit will be 20 times i.e 2b
  where b is the base here as it is decimal base is 10...
  similarly 1 to 1000 it is 3b^2...
  1 to 10000 it is 4b^3...
  from these ans is 3b^2-2b=280
• 11 years agoHelpfull: Yes(7) No(0)
• number of nos that can be formed =9*10*10 =900
  now, exclude 2 from set i.e. {0,1,3,4,5,6,7,8,9}
  and form 3 digit no i.e. 648
  so number of digits with 2 =900-248
  i.e. 252
  guys its the best I came up with , you could verify it with number of 2's b/w 11 & 100 and its 18
• 11 years agoHelpfull: Yes(5) No(0)
• ans = 300.
• 11 years agoHelpfull: Yes(2) No(7)
• 28on putting 2 on unit place we have 90
  on putting 2 on tens place we have 90
  on putting 2 on hundred place we have 100
  total 280
• 11 years agoHelpfull: Yes(0) No(1)
• 280
• 11 years agoHelpfull: Yes(0) No(1)
• supose 1 digit numbers 1b^0(b=10) 1*10^0=1
  2 digit number 2b 2*10=20
  3 digit number 3b^2 3*10^2=300
  
• 11 years agoHelpfull: Yes(0) No(0)
• @sireesha, thank u,your sol'n is perfect.
• 11 years agoHelpfull: Yes(0) No(0)
• 210
  from 0-100 2 will be written 11times(02,12,22,32,42,52,62,72,82,92)...
  this will be repeated for 9 times...
  from 200-299, there are 100 two's extra in the hundred's place...hence total number of twos in all the digits from 200-299 is 100+11=111
  hence total number of twos=9*11+111=210
• 11 years agoHelpfull: Yes(0) No(1)
• the answer is 280....
• 10 years agoHelpfull: Yes(0) No(1)