Why not put it in an auto enter tab of field options
Self * .01
Uncheck "Do not replace...."
I think you're looking for the Get ( ActiveFieldContents ) function.
I use this auto-enter calculation when the need arises and when the assumptions around which the expression is designed are appropriate:
If ( self > 1 ; self / 100 ; self )
and then I clear the "do not replace existing value" check box.
The "assumption" behind this calculation is that you will not need to enter percents greater than 100%.