260: Annual Factorial

Why don't we need a calculator for this?

Source: UVM, 2011

97: n!

It's a straightforward question today. Calculators are allowed for this question because we here do not feel that six-digit multiplication is worth the effort. I mean, we know you COULD do it, but that's what a tool is for, right?

For any confused students, this problem is not suggesting that 851 is special! That's factorial notation, n!, meaning multiply the integer n by all the positive integers less than n.  (Yeah, n must be a positive integer to begin with.)

For example, 6! = 6*5*4*3*2*1 = 720

For completeness, 0! = 1

Thanks to Darren, Right on the Left Coast, for this one.