This Long Period, However, May Be Reduced To Four Hundred Years; For Since The Dominical Letter Goes Back Five Places Every Four Years, Its Variation In Four Hundred Years, In The Julian Calendar, Was Five Hundred Places, Which Is Equivalent To Only Three Places (For Five Hundred Divided By Seven Leaves Three); But The Gregorian Calendar Suppresses Exactly Three Intercalations In Four Hundred Years, So That After Four Hundred Years The Dominical Letters Must Again Return In The Same Order.