Question

last ten four digit numbers​

Answer 1

If a four digit number is any string of four characters from 0-9 (so that 0001 and 0000 are four digit numbers) then we can reason as follows. Regardless of what number you chose for the first digit, there are 10 possible choices for the second digit. Thus there are 10 10 = 102 = 100 possible two digit numbers.

Answer 2

1000 is least four .digit number