[mjevans]

Constant 9 does match the expression ( at least when I truncate the output in KCalc 2^13*10^16/2^28 shows base16 0x470de4df82 )...

However, I don't know enough about floating point conversion to understand why that value's useful, or why it's stored where a fractional part normally would be in that same format.

Constants 6 and 7 visually appear to be in a similar fractional range and possibly as if extending precision of a fraction to 8 bit, 16 bit, and 32 bit words. I wonder if something along that line of thought might have an answer similar to the constant 10.

[kens]

The FPU supports decimal numbers in BCD (binary-coded decimal). Presumably these large powers of 10 are useful for BCD conversion, especially since they are near other BCD-related masks. But they aren't normal floating-point numbers, so they don't have exponent parts. Yes, constants 6 and 7 look like they should be part of the same sequence, but nothing that I try will work.