Question

How many integers from 10 through 99 have distinct digits?

Answer 1

Answer:

10............,.................

.....

Answer 2

$\huge{\textbf{{{\color{navy}{Ꭺŋ}}{\red{ѕw}}{\pink{єr ♤࿐  }}{\color {pink}{:}}}}}$

Since there are 9 ways to determine the 1st digit and (10 – 1 = 9) ways to determine the second digit, [9] × [9] = 81 So there are 81 integers from 10-99 with distinct digits.