Description: Define the "decimal fraction constructor", which is used to build up "decimal fractions" in base 10. This is intentionally similar to df-dec . (Contributed by David A. Wheeler, 15-May-2015) (Revised by AV, 9-Sep-2021)
|- _ A B = ( A + ( B / ; 1 0 ) )
|- A
|- B
|- _ A B
|- +
|- /
|- 1
|- 0
|- ; 1 0
|- ( B / ; 1 0 )
|- ( A + ( B / ; 1 0 ) )