I found you can have as many exclamation points as you wish. This opens up lots of possibilities, and maybe is cause for headaches. A triple factorial multiplies every third factor, etc. Something like 9!!!!!!! multiplies every 7th number in the sequence down, so it is 9 x 2 = 18.

8!!!, for example is 8 x 5 x 2 = 80. Thus 10 more solutions are 8!!! ** 0 = 80, 8!!! ** 1 = 81, 8!!! + 2 = 82, etc.