using the standalone nasal binary in FG's bin directory, printf seems to be missing... i've not tried this from within FG using the nasal console...
using the attached nas file, i get the following output:
In hexadecimal, 100000 = 186A0
Runtime error: undefined symbol: printf
at /home/myuser/fg/next/install/flightgear/fgdata/Nasal/nasaltest1.nas, line 4
called from: /home/myuser/fg/next/install/flightgear/fgdata/Nasal/nasaltest1.nas, line 1
yes, there's a defect in the example line given but i corrected it in my attached test file...
i don't know what happened to the link to the wiki page that i put in the original report above :(
here it is again but raw this time instead of trying to use the link function...
https://wiki.flightgear.org/Nasal_library#printf.28.29
Just checked, the printf function just calls sprintf, but that alias is defined by FGData/Nasal/globals.nas, which of course is not loaded by standalpone Nasal.
So, in standalone, use sprintf, is the answer. (or just everywhere, I guess, since it always works)