Simplify the following text for a Grade 15 native English-speaking person.
Original: This policy does not forbid routine calculations , such as adding numbers , converting units , or calculating a person 's age , provided editors agree that the arithmetic and its application correctly reflect the information published by the sources from which it is derived .
Simplified: This policy allows routine mathematical calculations , such as adding numbers , converting units , or calculating a person 's age , provided editors agree that the arithmetic and its application correctly reflect the sources .