A floating point number consists of a normalized mantissa and an exponent, so that

M * 10 ^ E

is your number. A mantissa is normalized if it has only one digit in the rand 1...9 before the decimal point.

Have a look at

http://babbage.cs.qc.edu/courses/cs341/IEEE-754.html

This also shows the "biasing" of the exponent. In the simplest case, the exponent biasing simply means it is a signed integer (like with IEEE 32 bit floats). But you can shift the exponent range either way, depending on your needs (if you need rather small or big numbers).

Cheers,

Stefan