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Numerical Ability
Permutation and Combination
Q. Find the total number of four digit numbers that can be formed using the digits 1,2,5,6.
Read Solution (Total 17)
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- no. will be formed by taking all at a time with repititon allowed
total=4*4*4*4=256 - 11 years agoHelpfull: Yes(32) No(7)
- unit place can we fill by any number so 4 ways of filling
ten place filled any of remaining 3 numbers
hundreds place filled any of remaining 2 numbers
last we have 1 number
required number=4*3*2*1=24 - 11 years agoHelpfull: Yes(31) No(7)
- If repitition is allowed then 4*4*4*4=256
If repitition is not allowed then 4*3*2*1=24 - 11 years agoHelpfull: Yes(29) No(0)
- sum of four digit numbers that can be formed from 1,2,5,6?
total no. formed = 4!=4*3*2*1=24
starting with 1 = 3*2= 6 no.s
starting with 2 = 3*2= 6 n0.s
starting with 5 = 3*2= 6 no.s
starting with 6 = 3*2= 6 no.s
sum of digits starting with 1,2,5,6 = 6*1+6*2+6*5+6*6=6*(1+2+5+6)=84
this sum will be same for hundred, tens & unit places
sum of all 4 digit numbers formed using digits 1,2,5,6
= 1000*84+100*84+10*84+84
=84*(1000+100+10+1)
=84*1111
=93324
- 11 years agoHelpfull: Yes(24) No(15)
- In this question they didn't mentioned that the repetetion of number is not allowed.
so if repetetion allowed then the answer should be 4*4*4*4=256;
If repetetion not allowed then answer is 4*3*2*1=24; - 11 years agoHelpfull: Yes(9) No(0)
- (4-1)!(1111)(1+2+5+6)
- 11 years agoHelpfull: Yes(6) No(0)
- Please correct the question as:find the total sum of four digit numbers that can be formed from 1,2,5,6?
- 11 years agoHelpfull: Yes(3) No(0)
- 4! = 4*3*2*1 = 24
- 11 years agoHelpfull: Yes(1) No(0)
- 4p4 = 4!/0! =24
- 11 years agoHelpfull: Yes(1) No(0)
- generalized formula:
(n-1)!(11111.....)(sum of digits)
[(total number of numbers - 1)(1's equal to numbers of digits)(sum of given digits) - 10 years agoHelpfull: Yes(1) No(0)
- if reapetation is allowed then 256 else 24
- 10 years agoHelpfull: Yes(1) No(0)
- 3!*3!*3!*3!
- 11 years agoHelpfull: Yes(0) No(3)
- Raghav gupta's ans is right..
- 11 years agoHelpfull: Yes(0) No(0)
- @Nishant Nishikar bhai tumhara solution 100% correct hain .....
- 11 years agoHelpfull: Yes(0) No(0)
- Since repetition is allowed so each place can be filled in 4 ways.
Total = 4^4 = 256 - 10 years agoHelpfull: Yes(0) No(0)
- case 1(without repeat) : 4 digit number to be formed from 4 digit(1,2,5,6) = 4*3*2*1 = 24
case 2(with repeat) : 4*4*4*4= 4^4=256 - 10 years agoHelpfull: Yes(0) No(0)
- thousand place*hundreds place*tens place*unit place=4*3*2*1=24 .
- 9 years agoHelpfull: Yes(0) No(0)
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