IE @ @pbjïØ Üa@ @XR E E I EI . 7 ! = 2520 . 2 . () I . EI . IE IE IE IE .5! . 4 × 5!!+ 4 × 5! = 8 ×120 = 960 ABCDEFG () CBA CBA ABC .3! () . 5! . ABC D E F G . 3! × 5! = 6 ×120 = 720 10 (1 0 ) 1