We are the smallest and largest whole number that round to 8,000 when rounded to the nearest thousand.

The rule normally works that 0 to 4 is rounded down and 5 to 9 is rounded up. So the lowest number would be 7,500 (to the nearest thousand you would round the "5" up to turn the "7" in to an "8"). The highest whole number is 8,499. Any higher and that "4" would become a "5" meaning you would round up to 9000 and not down to 8,000.