REM Digital root
DATA 1&, 14&, 267&, 8128&, 39390&, 588225&, 627615&
FOR I = 0 TO 6
  READ A&
  N& = A&
  Base = 10
  GOSUB CalcDRootAndPers:
  PRINT A&;
  PRINT Pers;
  PRINT Root
NEXT I
END

CalcDRootAndPers:
REM Results: Root - digital root; Pers - persistance
Pers = 0
WHILE N& >= Base
  S = 0
  Loop:
    NModBase& = N& MOD Base
    S = S + NModBase&
    N& = N& / Base
    IF N& > 0 THEN Loop:
  Pers = Pers + 1
  N& = S
WEND
Root = N&
RETURN