6.1.0030
#
number-sign
CORE
 
( ud1 -- ud2 )

Divide ud1 by the number in BASE giving the quotient ud2 and the remainder n. (n is the least significant digit of ud1.) Convert n to external form and add the resulting character to the beginning of the pictured numeric output string. An ambiguous condition exists if # executes outside of a <# #> delimited number conversion.

Testing:
: GP3 <# 1 0 # # #> S" 01" S= ;
T{ GP3 -> <TRUE> }T