How do you get the least possible number that can be rounded off?

Answer 1

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.