Yes, it is true to a certain that the number of outer shell electrons determines the chemical properties of an element, only because this determines how the element interacts with other elements.
It has to due with numbers so I would say the last one!
Answer:
you can use math as a banker, a doctor, a scientist, the president probably uses math, you use math to see how much less juice you gave your sibling, and you can use math to help in collage! (sorry if its wrong tell me if it is)
