Elitmus
Exam
Numerical Ability
Permutation and Combination
Let S be the number of 6 digit numbers formed by using 1,2,3,4,5,6 without repetition and R be the number of 5 digit numbers formed by 1,2,3,4,5,6 without repetition. Find S-R.
Read Solution (Total 11)
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- Answer = 0;
---------Explanation------
It can be done using Factorial :-
As we need without repetition. So same digit can't be used twice.
S=6*5*4*3*2*1 = 6!
R=6*5*4*3*2 = 6!
So , S - R = 0 - 7 years agoHelpfull: Yes(21) No(0)
- There are 8 numbers divisible by 4.
numbers ends with xyzq12
xyzq16
xyzq24
xyzq32
xyzq36
xyzq52
xyzq56
xyzq64
Still four places are there for xyzq, so 4! possible(without repetition). Totally 8 number, ultimately 4!*8=192.
3!*8=48.
192-48=144.
Final answer is 144. - 7 years agoHelpfull: Yes(4) No(1)
- What are my chances...?
Verbal = 74.80
Problem Solving = 52.14
Quantitative = 65.22 - 7 years agoHelpfull: Yes(3) No(10)
- Sorry, I forgot to mention that "both the 5 & 6 digit numbers should be divisible by 4". I think answer will still be 0.
Thanks Utkarsh. - 7 years agoHelpfull: Yes(2) No(0)
- 6-digit nos. using 1,2,3,4,5,6 without repetition =6!=720
5-digit nos. using 1,2,3,4,5,6 without repetition =6p5=720
so, S-R=0 - 7 years agoHelpfull: Yes(2) No(0)
- 0
s=6*5*4*3*2*1
r=6*5*4*3*2
hence:s-r=0 - 7 years agoHelpfull: Yes(2) No(0)
- Wali ,if question says numbers must be divisible by 4 then,
S=4! x 8
R=3! x 8 so, S-R=192-48=144 - 7 years agoHelpfull: Yes(2) No(6)
- 6!-5! = 5!(6-1) = 120*5=600
- 7 years agoHelpfull: Yes(0) No(6)
- 0
S= 6!
R=6P5
S-R=6!-6!=0 - 6 years agoHelpfull: Yes(0) No(0)
- the answer will be 0 as the total number can be formed with the digits 1,2,3,4,5,6 is 6! and the total number formed by digits 1,2,3,4,5,6 is also 6*5*4*3*2 so S-R=0
- 5 years agoHelpfull: Yes(0) No(0)
- answer=0
first we check for S:
it is a 6 digit number __ __ __ __ __ __ , so first position will have 6 possibilities
second position has 5 possibilities as repetition not allowed
third possition has 4 possibilities and so on...
S=6*5*4*3*2*1=720
similarly we can check for R:
R=6*5*4*3*2=720
S-R=0 - 7 Months agoHelpfull: Yes(0) No(0)
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