Nitrogen, Oxygen, and Fluorine do not follow this trend. The noble gas electron configuration will be close to zero because they will not easily gain electrons.
To allow for equations and problems in chemistry to be as precise as possible. When experiments are conducted, and even if the number is the slightest bit off, the problem or experiment could be impacted very negatively. It allows for complete accuracy to ensure nothing goes wrong, since chemistry is very touchy and risky when dealing with extremely unsafe elements.
