Simplify the following text for a Grade 7 native English-speaking person.
Original: The AD\/BC notation does not use a year zero ; however , astronomical year numbering does use a minus sign , so `` 2 BC '' is equal to `` year -1 '' .
Simplified: The AD\/BC notation does not use a year zero . Scientific notation does , however , uses a minus sign , so ' 2 BC ' is equal to ` year -1 ' .