Your friend and your cousin discuss measuring with a ruler. Your friend says that you must always line up objects at the zero on a ruler. Your cousin says it does not matter. Who is correct, and why?
friend; A measurement always starts with a value of zero.
friend; A ruler does not match numbers one to one unless the measurement starts at zero.
cousin; you can choose any number for the start of the object and any number for the end.
cousin; The distance is the absolute value of the difference of the numbers lined up with the beginning and the end of the object.