Question

how many integers are there from 1 through 999 that have distinct digits​

Answer 1

$\huge \fcolorbox{purple}{lavenderblush}{ αηѕωєя♡}$

The answer is 9999 − 1000 + 1 = 9000. Another way to think about it: They are the integers from 1 to 9000 with 999 added to each, so clearly there are 9000 of them

Answer 2

Answer:

Solution. The answer is 9999 − 1000 + 1 = 9000. Another way to think about it: They are the integers from 1 to 9000 with 999 added to each, so clearly there are 9000 of them