The limits are 1.8e-38.7 to 3.4e38.7, now if you understand what that means; eh.
Now the key thing to note is the 7 Significant Figures... because this denotes the PRECISION that is available.
Sure with the Exponent we can describe very large or very small numbers., but the crux is that these are only to the 7 most important values; or more specifically this is what will be accurately calculated; as more figures will be returned but will exponentially become less accurate due to rounding errors and affine alignment.
I mean think of a Digital Volume Control... you will usually get 100 Points of Volume out of it., were-as an Analog Knob can allow you to be more refined but this is at the cost of allowing for Precise Volume Control.
The same is true between an Integer and Floating Point., greater range / fine tuning but at the loss of precision.