短的ab类型就比较容易，
如5*8=40很容易记住，

但是51*96=4896就很难记了，如何增加记忆长度和宽度？

还有51*96+36*47+447906894*4321=1935405695562就根本记不住了！！

再如英语，I don`t like FRANCH.就容易记忆，
但是，Just as bosses and boards have finally sorted out their worst accounting and compliance troubles, and improved their feeble corporation governance, a new problem threatens to earn them -- especially in America -- the sort of nasty headlines that inevitably lead to heads rolling in the executive suite: data insecurity.难记因为这样的长句信息量太大太多了！！