It is: 3450
145 is the least number that can be rounded to 150.
Any number such that 3535 < x ≤ 3545.
3500
The least number that can be rounded to 400 (to the nearest 400) is 200.
500,000 is the least whole number that can be rounded to the nearest millions.
3500
3500
3500
3500
3500
3500