History of Hindu Mathematics: A Source Book v1.c8.s4.92

v1.c8.s4.92

**Cross Multiplication Method.** This method has been mentioned by Śrîdhara, Mahâvîra, Śrîpati and some later writers as the *tastha* method. These writers, however, do not explain the method. Śrîdhara simply states: "The next (method) in which (the multiplier) is stationary is the *tastha*."² The method is algebraic and has been compared to *tiryak-guṇana* or *vajrâbhyâsa* (cross multiplication) used in algebra.³ It has been explained by Gaṇeśa (*c.* 1545) thus: