A calendar comprising a medium upon which a plurality of indicia are applied, wherein each of the indicia coacts with an adjacent indicia, and wherein each of the indicia is visually indicative of a complete lunar day and a complete solar day. Each indicia for the lunar day coacts with two indicia for the solar day and each indicia for the solar day coacts with two indicia for the lunar day. Additionally, the calendar comprises an interlocking notched indicia weekday banner, wherein the interlocking notched indicia weekday banner represents the relation between the seven days of a Jewish week and the seven days of a secular week. Furthermore, each indicia may form a plurality of indicia identifying a respective plurality of days, a respective one or more weeks, a respective one or more months, or a respective one or more years.