Do you have a text book or any scripts from your lecture?
Lookup the terms there first, then understand the context of the formula, ask your teacher if you have any unclear items.
Check the internet for floating point standards, e.g.
http://en.wikipedia.org/wiki/IEEE_floating_point[
^].
Check what a fixed-point number is, e.g.
http://en.wikipedia.org/wiki/Fixed-point_arithmetic[
^]. See also floating point:
http://en.wikipedia.org/wiki/Floating_point[
^].
Cheers
Andi
PS: As a hint: the fixed-point number must be capable to store all values that the floating-point number can store. Find out first, what the maximum floating-point number is. Then the minimum (most negative value if it is about positive *and* negative numbers). Then find the number closest to zero (the smallest, the one with the highest negative exponent and taking in consideration the k bits that are even below that number).
I get roughly calculating something like 70 bits and the fixed point somewhere shy above 50.