(phixonline)-->
with javascript_semantics
procedure digital_root(atom n, integer base=10)
integer root, persistence = 1
atom work = n
while true do
root = 0
while work!=0 do
root += remainder(work,base)
work = floor(work/base)
end while
if root<base then exit end if
work = root
persistence += 1
end while
printf(1,"%15d root: %d persistence: %d\n",{n,root,persistence})
end procedure
digital_root(627615)
digital_root(39390)
digital_root(588225)
digital_root(393900588225)