>>120 python
from operator import mul
def kake(n, ls):
＿＿m = reduce(mul, map(lambda x:int(x), list(str(n)) ) )
＿＿ls.append(m)
＿＿if len(str(m)) == 1:
＿＿＿＿return
＿＿kake(m, ls)

test = [0, 1, 9, 11, 15, 51, 52, 61, 66, 77, 93, 123, 277777788888899]
for n in test:
＿＿ls = []
＿＿kake(n, ls)
＿＿print "n="+str(n)+", "+"list="+str(ls)+", "+"len="+str(len(ls))+", "+"last="+str(ls[-1])

実行結果
n=0, list=[0], len=1, last=0
n=1, list=[1], len=1, last=1
n=9, list=[9], len=1, last=9
n=11, list=[1], len=1, last=1
n=15, list=[5], len=1, last=5
n=51, list=[5], len=1, last=5
n=52, list=[10, 0], len=2, last=0
n=61, list=[6], len=1, last=6
n=66, list=[36, 18, 8], len=3, last=8
n=77, list=[49, 36, 18, 8], len=4, last=8
n=93, list=[27, 14, 4], len=3, last=4
n=123, list=[6], len=1, last=6
n=277777788888899, list=[4996238671872L, 438939648, 4478976, 338688, 27648, 2688, 768, 336, 54, 20, 0], len=11, last=0