The first.
The least number that can be rounded off to 80 to the nearest integer is 75.
8.55 and 5.445
6,500 rounded to the nearest thousand is then 7,000
12.6500...001 where you keep adding 0s. 12.65 should be rounded DOWN to 12.6, not up to 12.7.
The least possible number that can be rounded off to 10.72 10.652
The least possible number that can be rounded off to 25000 is 24995.
5000
The least number that can be rounded to 400 (to the nearest 400) is 200.
8.345 can be rounded to 8.35
350
0.5
0.5
0.5
It is: 3450
12.65
750