How many $$4 $$ digit numbers are there?
Correct option is B. $$9000$$
The largest $$4-$$digit number $$= 9999$$
The smallest $$4-$$ digit number $$= 1000$$
Total number of $$4-$$digit numbers $$= (9999 - 1000) + 1$$
$$ = 8999 + 1$$
$$ = 9000$$
Hence option (b) is correct answer