假設原本有$10, 用$8買雞, 剩$2
/ q/ s! x0 b+ S7 _. mtvb now,tvbnow,bttvb之後$9賣出, $2+$9 = $11tvb now,tvbnow,bttvb6 d7 b& s( k% G o7 p6 _! D
再用$10買雞, $11-$10 = $18 E& s9 p7 X6 ~, |8 L$ D& p1 l- T
又再以$11賣出, $1+$11 = $12tvb now,tvbnow,bttvb. O2 `( F( S# p ]
$12-$10 = 賺$2 |