Elitmus
Exam
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How many six digit number can be formed using the digits 0 to 5, without repetition such that the number is divisible by the digit at its unit place?
a)420 b)426 c)432 d)none of the above
Read Solution (Total 10)
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- first we need to think about digit(0,1,2,3,4,5)
if number is end with 0 than 0
if number is end with 1 than _ _ _ _ 1=4*4*3*2=96
4 4 3 2
if number is end with 2 than 4*4*3*2=96
if number is end with 3 than 4*4*3*2=96
if number is end with 4 than _ _ _ 0 4=4*3*2=24 and _ _ _ 2 4=3*3*2=18
if number is end with 5 than 4*4*3*2 = 96
total=0+96+96+96+(24+18)+96 = 426
ans:B - 9 years agoHelpfull: Yes(21) No(0)
- Total number of numbers with digit (0,1,2,3,4,5) with starting and last digit as not zero is...
480 (i.e 5*4*3*2*1*4=480)
Now for these total numbers subtract those which are out of the case....here when the last two digit will be 14 or 34 or 54 then it will not be divisible by 4. Hence,
total number of numbers with last two digits as (14 or 34 or 54) = 18*3 = 54
ans = 480-54 = 426 - 9 years agoHelpfull: Yes(4) No(0)
- b)426
no. cannot end with zero as any number divided by 0 is undefined
no. ends with 1 then 5!
no. ends with 2 then 4*4! (0 cannot be placed at 1st position)
no. ends with 3 then 4*4!
no. ends with 4 then 3*3!
no. ends with 5 then 4*4!
=426 - 9 years agoHelpfull: Yes(3) No(0)
- c) 432
Numbers ending with 1,2 3,5 are 96 each and ending with 4 are 2*24 - 9 years agoHelpfull: Yes(1) No(4)
- Numbers ending with 1,2,3,5 are 4*4!=96 and number ending with 4=18+24=>42 because 10th position may hold 0 or 2.So for 04 total number will be 4! and for 24(ending with 24) number will be 3*3!,total number is 96*4+24+18=426
- 9 years agoHelpfull: Yes(1) No(1)
- as everyone no for 1,3,5,2 ====96 but be careful for 4 as number divisible by 4 only when its lat two digit is divisible by 2 so ----04 nd ----24 for which 24+18 so tatal of 426 numeber possible
- 9 years agoHelpfull: Yes(1) No(0)
- first we need to think about unit digit (0,1,2,3,4,5)
so if no. ends with 0 then 5!
if no,,ends with 1 then 5!
if no,,ends with 3 then 5! (if we add all the no...divisble by 3)
if no,,ends with 2 then 4*4!(we cant place 0 at 1st position, fix last no as 2)
if no,,ends with 4 then 3*3!(no to be divisible by 4 we should think about last two digit i.e 24 rest no's are already included in 2)
if no ends with 5 then 4*4!
total 474 option d will be the ans.. - 9 years agoHelpfull: Yes(0) No(2)
- answer is c) 432
Numbers ending with 1,2 3,5 are 96 each and ending with 4 are 2*24(this is correct)
no ending with 4 can have 0 or 2 at the tens place..4*3*2*1*2*1=48
96+96+96+96+48=432
- 9 years agoHelpfull: Yes(0) No(2)
- Sorry my mistake 0 option can't be check and ans will be 432
- 9 years agoHelpfull: Yes(0) No(2)
- how is any number ending with 3, divisible by 3. ex: 23, 101123( six digit number). these are not divisible by 3.
- 9 years agoHelpfull: Yes(0) No(1)
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