If we need a 7, this is the ones column, the twos, fours, eights, so here are our columns and this was our decimal system a moment ago, and I wanna express the number 7 and the only digits 0 I now have access to are zero and one, whereas, in decimal, dec meaning 10. 如果你需要7,这是一位,二位,四位,八位,这是位数,刚才说的十进制的位数,我想表达7而且,只能采用数字1与,在十进制中, dec 意思是十。 哈佛公开课 - 计算机科学课程节选