Use the following notation to perform these types of calculations.
I thought it was a rather odd behavior of Google Spreadsheets and therefore I started to investigate the situation.
It started by performing the calculation in the Google Calculator:
There, the notation
was re-written to
This solves your problem immediately. Entering the last formula (with
ROUND()) in Google Spreadsheets, will give you : -1. But why?
In the first reference, Dr. Math is explaining the matter in detail. Bottom line is that the calculation is returning an imaginary number, like the cube root of -1.
To avoid these calculations, the minus is simply extracted from the calculation and "added" afterwards.
- Dr. Math
- There's no bug