There was a nice little blog post on Good Morning Silicon Valley that led to another, really interesting blog post titled "Arithmetic is Hard--To Get Right."  Turns out there are "...exactly 12 instances out of the 9 quintillion possibilities it [Excel] goes completely bonkers" and 77.1 x 850 is one of them. 

I tried it and did indeed, get 10000 instead of 65535.

The original post is here