Excel, 2007

77.1*850

displaying 100,000

should give you 65,535

I did work on the Excel team

but

thirteen years ago

Excel keeps numbers, internally, in a binary format, but displays them as strings

77.1

0100 0000 0101 0011 0100 0110 0110 0110
0110 0110 0110 0110 0110 0110 0110 0110

This is the code that has the bug that causes a few numbers which are extremely close to 65,535 to be formatted incorrectly as 100,000.

This is still only a bug in the number formatting code; if you try to make a chart with that number in it, you'll get a correct chart.

how to represent floating point numbers in binary, and this is what almost everybody uses, including Excel

the chance of this bug actually mattering to you as an individual is breathtakingly small.

testing done on the Excel team is done automatically with

VBA code

Cells containing this value display as 100,000

but from VBA, they're going to look like 65,535

Why not use "exact" (decimal) arithmetic?

slow

Calculator

it doesn't have to be as fast as Excel