Question

How many four-digit natural numbers can be written using the digits 1,2,3, and 4 once each?

Answer 1

1234
1324
1423
2134
2314
2413
3124
3241
3412
4123
4231
4312
therefore 12 no.s cancel be formed the 4digits
just try to combine the no.s

Answer 2

${\huge\star\bf{\mathfrak{Hello Mate}\star}}}$

There are so many numbers that can written by using these numbers.

=> 1234
=> 1243
=> 1324
=> 1342
=> 1423
=> 1432
=> 2143
=> 2134
=> 2314
=> 2341
=> 2431
=> 2413
=> 3124
=> 3142
=> 3241
=> 3214
=> 3421
=> 3412
=> 4213
=> 4231
=> 4123
=> 4132
=> 4321
=> 4312


Thanks
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