So basically you have to multiply 100 by every single number after it like 100*99*98*97*96......
Hope this helps!
you meant 100!, is a factorial, and yes, your calculator has [ ! ] button for factorials
5! is just 5*4*3*2*1
11! is just 11*10*9*8*7*6*5*4*3*2*1
and so on.