There is a further group of metric cycles recognized in conventional musical theory. Duple, triple, and quadruple time are called simple time signatures. When each beat of a simple time signature is subdivided into three, the equivalent compound time signature is obtained. Compound duple time—in other words, 6/8—thus has six beats. Compound triple time (9/8) has nine beats, while compound quadruple time (12/8) has twelve beats. See Figures 7.8 through 7.10 for examples of each.