Sentence:  The generic <WSD>quadratic form</WSD> of even dimension "n" with trivial discriminant over an arbitrary field of characteristic different from 2 containing a square root of −1 can be written in the Witt ring as a sum of 2-fold Pfister forms using n − 2 terms and not less. The number of Pfister forms required to express a <WSD>quadratic form</WSD> of degree 6 with trivial discriminant is determined in various cases. 
Meaning of the word marked with <WSD> tags:  A homogeneous polynomial of degree 2 in a given number of variables.