P philomina New member Joined Oct 31, 2010 Messages 7 Nov 7, 2010 #1 Can anyone please help me with this question. How many different four digit numbers are there if no digit is repeated? Answer options are: a) 4 b) 24 c) 504 d) 4536
Can anyone please help me with this question. How many different four digit numbers are there if no digit is repeated? Answer options are: a) 4 b) 24 c) 504 d) 4536
D Denis Senior Member Joined Feb 17, 2004 Messages 1,700 Nov 7, 2010 #2 Each leading digits 1 to 9 (0 can't be a leading digit, I assume) produces 9! / 6! 4digit numbers. If that's not enough, then you need help from your teacher.
Each leading digits 1 to 9 (0 can't be a leading digit, I assume) produces 9! / 6! 4digit numbers. If that's not enough, then you need help from your teacher.
D Deleted member 4993 Guest Nov 7, 2010 #3 philomina said: Can anyone please help me with this question. How many different four digit numbers are there if no digit is repeated? Answer options are: a) 4 b) 24 c) 504 d) 4536 Click to expand... The first digit - 1000 th position - can be filled with 9 numbers (0 not allowed) ................. ..............................9 ways The second digit can be filled with 9 numbers (any number except the number chosen above)..............................9 ways The third digit can be filled with 8 numbers (any number except the numbers chosen above)..............................8 ways The third digit can be filled with 7 numbers (any number except the numbers chosen above)..............................7 ways
philomina said: Can anyone please help me with this question. How many different four digit numbers are there if no digit is repeated? Answer options are: a) 4 b) 24 c) 504 d) 4536 Click to expand... The first digit - 1000 th position - can be filled with 9 numbers (0 not allowed) ................. ..............................9 ways The second digit can be filled with 9 numbers (any number except the number chosen above)..............................9 ways The third digit can be filled with 8 numbers (any number except the numbers chosen above)..............................8 ways The third digit can be filled with 7 numbers (any number except the numbers chosen above)..............................7 ways
