It would help to know which digit.
0 appears in 9 numbers
and each of the others in 18 numbers.
17
There are 9000 4-digit numbers. 8*9*9*9 = 5832 of them do not contain a 5 The remaining 3168 contain a 5.
-2
-5
252
17
There are 9000 4-digit numbers. 8*9*9*9 = 5832 of them do not contain a 5 The remaining 3168 contain a 5.
-2
1
-5
252
The pages of a book are numbered from 1 to 128. How many page numbers contain the digit 6?
There are 6804 such numbers.
648
-5
There is no smallest whole number - negative numbers go on forever. Therefore, there are infinitely many whole numbers that are smaller than the greatest 2-digit number.
874