This is a common occurrence: expecting zero and getting very close to it. It
all has to do with IEEE 754 and the way Excel (and most other computer apps)
convert decimal numbers (numbers using base 10) to binary numbers (numbers
using base 2).
Only a problem with real numbers (i.e. numbers with decimal places) not with
How to avoid: round to 12 decimal places =ROUND(COS(RADIANS(90)),12)
You handheld calculator does this automatically, so you never see it with