sum_digits = proc (n, base: int) returns (int)
    sum: int := 0
    while n > 0 do
        sum := sum + n // base
        n := n / base
    end
    return (sum)
end sum_digits

digital_root = proc (n, base: int) returns (int, int)
    persistence: int := 0
    while n >= base do
        persistence := persistence + 1
        n := sum_digits(n, base)
    end
    return (n, persistence)
end digital_root

start_up = proc ()
    po: stream := stream$primary_output()
    tests: array[int] := array[int]$[627615, 39390, 588225, 393900588225]

    for test: int in array[int]$elements(tests) do
        root, persistence: int := digital_root(test, 10)
        stream$putl(po, int$unparse(test)
                        || " has additive persistence "
                        || int$unparse(persistence)
                        || " and digital root of "
                        || int$unparse(root))
    end
end start_up