df -h shows insufficient precision

[Zenaan Harkness <zenaan@freedbms.net>]

A regular itchy annoyance for years now:

df shows bytes, df -h shows only one decimal place, so e.g. on a
1.8TiB drive "1.6T" is the free space, but that resolution/ precision
is insufficient. Of course I can fire up bc, set scale=20 and do some
powers of 1024 division, but that's all very clunky.

How hard would it be to add an option to bc, to choose the number of
decimal places to use in the output, or the number of digits of
precision to display?

TIA,