I need to be able to enter data in one of two ways, but have it result in the
same value. For example,

I need to be able to enter the decimal number '11.22' as
11.22 or <-- I know how to do that :-)
1122 <-- and that :-)
but in the end, the number needs to be understood as '11.22'

So basically my problem is that I'm either stuck with one data entry method,
or another, but I can't seem to find a way to use both in the same cell.
I've toyed with the data validation feature, but I haven't found a way to
make it do what I want.