Not much more. When we say 6 digits, we're talking in decimal numbers. A floating point value has a mantissa of 23 bits (if you don't count the sign), which makes the max number be 8388608. So that's between 6 & 7 digits.
[EDIT]Crosspost, this was a reply for EpicBoy.
[EDIT]Crosspost, this was a reply for EpicBoy.