PHOTOCHEMICAL CHANGES INDUCED BY ULTRAVIOLET LIGHT OR EVEN BY THE BROAD SPECTRUM OF VISIBLE SUNLIGHT ( AQ-374 THE DEEP, HOT BIOSPHERE ). AQ 43 = PI ( GRK-80 π ~ AQ-8 3.14 or AQ-11 22/7 is close enough, although engineers often use 3.1416 (5 significant figures) or 3.14159 (6 significant figures)