"float" on 3 bytes

[tsalm]

Hi,

I need to minimize the size of my memory use...
My program uses a big array of float.
My float have a gap of 0.0000001 and 65536.

So i think to store one sort of "float" with :
- an "ushort" to have numbers
- and a "ubyte" to have the number of digit in the decimal portion (or  
something like this...).

What could be the better way for you ?

Thanks in advance for your help,
TSalm