It is the target value less half the amount of rounding.
If that sounds cryptic, try this example:
Find the smallest number which, when rounded to the nearest 10 comes to 400.
Target Value = 400
Amount of Rounding = 10
So the smallest value = 400 - 10/2 = 400 - 5 = 395.
The smallest number rounded to the nearest 100, which comes to 400, is
400 - 100/2 = 400 - 50 = 350.
The least possible number that can be rounded off to 25000 is 24995.
It is: 3.25
5.445
8.55
85500
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.
8.345 can be rounded to 8.35
25450
It is: 3.25
5.445
8.55
85500
550
24500
1999 is the greatest possible number which can be rounded off to 2000, which has 1500 as the least.
8.55 and 5.445