general_fact: 91 is the amount of money one has if one has one coin of each U.S. denomination less than a dollar (penny, nickel, dime, quarter, half dollar) in cents.
math_fact: 91 is a repdigit in base 9 (111).
trivia: 91 is the code for international direct dial phone calls to India.
historical_date: March 31st is the day in 1986 that a Mexicana Boeing 727 en route to Puerto Vallarta erupts in flames and crashes in the mountains northwest of Mexico City, killing 166.