how many4digit number are there with no digit repeated between 1,2,3,4,5,6,7,8,9?

Question

this question is from PERMUTATION AND COMBINATION of standard 11(NCERT).

Answer 1

ANS.
4536 4-digit numbers

EXPLANATION:
1st digit must be between 1-9 i.e. 9 possibilities
If 1st digit is fixed,
2nd digit can be between 0-9 but should not be the same as the 1st digit i.e. 9 possibilities
If 1st and 2nd digits are fixed, then for 3rd digit there are 8 possibilities and for 4th digit there will then be 7 possibilities.

Hence, different combinations possible are 9*9*8*7 = 4536.

Answer 2

2

Answer 3

Combinations of 4 elements taken from 9, that is

9!/ [4! (9-4)!] = 9*8*7*6 / (1*2*3*4) = 9* 7 * 2 = 126

There are 126 possibilities of 4 digit numbers with no digit repeated (0 not taken into account).
This is a COMBINATION problem.

Answer 4

_ _ _ _

Take those 4 blanks to be the 4 digit number that needs to be formed.

In the first slot, we can put any one of the 9 numbers, thus we have 9 choices. The second slot would have a choice less as one number has already been used in the first slot. Likewise the third slot would have 7 choices and the fourth 6. Thus the answer would be 9 permutate 4, or 9 * 8 * 7 *6.

ans:3024.

Answer 5

Smallest 5 digit quantity is ten thousand best 4 digit quantity is 9999 ten thousand-9999=a million It happens with alright here. that's a theorm, Smallest n digit no - best n-a million digit no = a million that's proved as, 10-9=a million one hundred-ninety 9=a million 1000-999=a million ten thousand-9999=a million one hundred thousand-99999=a million It is going on...

Answer 6

9*8*7*6 different numbers where the digits can nt be reused ( 1123 wrong, 1234 ok )

Answer 7

3024 because u would multiply 9, 8, 7, 6

Answer 8

= 9*8*7*6

=3,024

Answer 9

2468