Numbers does not have a feature that will take an entry from a cell, modify the value, then put the result in the same cell. You can, solve this two ways:
1) add a second column that takes input from the column where you enter the values, and performs the operation
2) create an Applescript which you run AFTER you enter the data which can modify the contents of each cell in the column using a particular scale factor
If you are entering the data in column A, then in column B enter the formula:
=A/100
select the cell, copy, now select the column, paste