Saved Bookmarks
| 1. |
How many 4-digit numbers are there with no digit repeated?☺️☺️☺️☺️☺️☺️ |
|
Answer» 9*8*7*6=? Total no of digits =44 vaccent places can be filled with10P 4 WAYS but this no include those no whi start with zero If we find zero at thousands place then the remaining 3 places can be filled with remaining 9 digits in 9p 3 ways so Total no of 4 digit no = 10p 4-9p 410!/(10-4)! -9!/(9-3)!10*9*8*7*6! - 9*8*7*6!--------------------- --------------6! 6!=90*56-72*7=5040-504=4536 ans Hope it will help you? |
|