Since numbers equal to or greater than 5 are rounded up, and numbers equal to or less than 4 are rounded down, the largest 4-digit number that can be rounded off to 3000 would be 3004.
2911 rounded to 1 significant figure is 3000.
3000
3499
3000
3000
If you include the number 3,000, there are exactly 2,001 4-digit numbers between 500 and 3000.
3000
3000
3000
3000
2500 is the least whole number that rounds to 3000 because the last significant digit is 5.