Theorem T45 ∏j=1n(1−aj)≥1−∑j=1naj\prod_{j=1}^n (1 - a_j) \geq 1 - \sum_{j=1}^n a_j j=1∏n(1−aj)≥1−j=1∑naj with 0<aj<10 < a_j < 10<aj<1.