mathematics in indigenous igbo society is evident in their calendar, banking system and strategic betting game called "okwe". in their indigenous calendar, a week had four days, a month consisted of seven weeks and 13 months made a year. in the last month, an extra day was added. this calendar is still used in indigenous igbo villages and towns to determine market days. they settled law matters via mediators, and their banking system for loans and savings, called isusu, is also still used. the igbo new year, starting with the month "ọ́nwạ́ m̀bụ́" () occurs on the third week of february, although the traditional start of the year for many igbo communities is around springtime in "ọ́nwạ́ ágwụ́" (june). used as a ceremonial script by secret societies, the igbo have an indigenous ideographic set of symbols called nsibidi, originating from the neighboring ejagham people. igbo people produced bronzes from as early as the 9th century, some of which have been found at the town of igbo ukwu, anambra state.