Abstract. In this paper we study the sequences defined by the last and
the last non-zero digits of nn in base b. For the sequence given by the last
digits of nn in base b, we prove its periodicity using different techniques
than those used by W. Sierpinski and R. Hampel. In the case of the
sequence given by the last non-zero digits of nn in base b (which had
been studied only for b = 10) we show the non-periodicity of the sequence
when b is an odd prime power and when it is even and square-free. We
also show that if b = 22s
the sequence is periodic and conjecture that this
is the only such case.