How many numbers are there in all from 6000 to 6999 (both 6000 and 6999 included) having at least one of their digits repeated ??

(a) 216
(b) 356
(c) 496
(d) 504

• total nos. between 6000 and 6999=1000
  nos. when no digits are repeated=9*8*7=504
  consider a four digit no. between 6000 and 6999
  at one's place=9 digits can be used (6 cannot be used as it used at 1000th place)
  at 10's place=8 digits can be used
  at 100's place 7 digits can be used
  at 1000's place only one digit can be used(i.e.6)
  reqd. nos.=1000-504=496
  c is correct option
• 10 years agoHelpfull: Yes(1) No(0)
• ans: c
  
  total no's are 1000
  now i will remove numbers which are not repeated from total
  so ,it is first digitis always 6 it is fixed
  and remaining 3 can be arranged from 9 digits in 9p3 ways
  so answer is 1000-9p3=1000-504=496
  
• 10 years agoHelpfull: Yes(1) No(0)