There are 6,750 such numbers.
500
8100
4500 of them.
Not counting numbers with leading 0s, there are 48 = 44 - 43
There are ten thousand possible pin numbers with four digits. To generate your list, start at 0000 and start counting, to 9999.
Lowest four-digit number: 1000 Highest four-digit number: 9999
9995
240
7000 - 999 ie 6001 four digit numbers
No, only positive integers are considered counting numbers.
900 numbers