How many 6 digit telephone numbers can be formed if each number starts with 35 and no digit appears more than once?


Option
1) 720
2) 360
3) 1420
4) 1680

• 3 and 5 are already used , so the remaining no's left are 8 so , now in next step we will select 4 numbers from 8 and this can be done by 8C4* 4! ( 4! these selected 4 digits can be arranged in factorial 4 ways )
  ans = 70*12= 1680
• 9 years agoHelpfull: Yes(8) No(2)
• we have to make 6 digit number...from which 2 digits are already given.so we are left with 4 digits and numbers from 0-9(exept 3 & 5)
  so we have to find number of ways to arrange 8 numbers (i.e. 0,1,2,4,6,7,8,9) in to make 4 digit number..so that 8P4=8! / 4! = 1680.
• 9 years agoHelpfull: Yes(8) No(0)
• 1*1*8*7*6*5 = 1680
• 9 years agoHelpfull: Yes(4) No(1)
• 6 digits telephone no can be formed by 10 digits, but form qustn each no start with 35 so we have 8 digits remaining so 4 places can be formed in 8*7*6*5=1680.
• 9 years agoHelpfull: Yes(3) No(0)
• 8*7*6*5=1680
• 9 years agoHelpfull: Yes(1) No(0)
• we have to fill 6 digit number
  35 - - - - so 8×7×5×6=1680
• 9 years agoHelpfull: Yes(0) No(0)
• And is1680
  bcoz let consider first. Two digit const as 35 and arrangement of remain 4 digit from 01246789 using 7p4..
  So ans=7*6*5*4=1680
• 9 years agoHelpfull: Yes(0) No(1)
• in 6 places like _ _ _ _ _ _ ,starting will be always 35 so that,digit will be from 0-9 here already 3 and 5 are present so remaining possible are 8!*7!*6!*5!=1680 i.e option:(4)
• 9 years agoHelpfull: Yes(0) No(0)
• As the no start with 35 so
  remaining no left is 8
  so 8*7*6*5*1=1680
• 9 years agoHelpfull: Yes(0) No(0)
• 1680 is riht
• 9 years agoHelpfull: Yes(0) No(0)
• 1680
  of 6 numbers 2 numbers are already given and remaining 8 numbers are there. so,8*7*6*5=1680
• 9 years agoHelpfull: Yes(0) No(0)
• 720
  6 digit number.. 6!
• 9 years agoHelpfull: Yes(0) No(1)
• we have 8 digits left to be placed in 4 places this can be done in'8 * 7 * 6 * 5 = 1680
• 9 years agoHelpfull: Yes(0) No(0)
• if each number starts with 35 so 1st 2 places are booked and remaining 4 places has to be filled with 8 numbers.This can be done in 8P4 ways =1680 ways
• 9 years agoHelpfull: Yes(0) No(0)
• There is 10 numbers from which we have to select 6numbers from the 6numbers 3 and 5 already took the place of 1st and 2nd (012_4_6789) 3 5 _ _ _ _ the next 4numbers can be select out of 8numbers by using MNP rules hence 8*7*6*5=1680
• 9 years agoHelpfull: Yes(0) No(0)
• 3 5 r fix 8 * 7 * 6*5 =1680
  __ __ __ __ __ __
• 9 years agoHelpfull: Yes(0) No(0)
• For a 6 digit no. First 2 digits are 35 hence to fill the 3rd digit we have 8 options , to fill the 4th one 7 and so on.
  
  Therefore, the answer will be
  8*7*6*5 = 1680
• 9 years agoHelpfull: Yes(0) No(0)
• 1680 since first two places can be filled with one way then 3 place with 8 then 7 then 6 then 5
  so 1*1*8*7*6*5=1680
• 9 years agoHelpfull: Yes(0) No(0)
• (0-9)= 9 digits. 35 fixed. Remaining digits=8. nos to be selected =4. 4 places can b filled in 4! ways
  SO...8c4*4!=70*24=1680
• 9 years agoHelpfull: Yes(0) No(0)
• 4 -> 1680
  as the first two digits are already reserved so remaining four places can be filled in 8*7*6*5 ways
  so ans is 1680
• 8 years agoHelpfull: Yes(0) No(0)
• 1680
  1*1*8*7*6*5=1680
• 8 years agoHelpfull: Yes(0) No(0)
• 1680
  8*7*6*5
• 7 years agoHelpfull: Yes(0) No(0)