For example, in the lesson on subtracting one-digit numbers from two-digit numbers, the first level is only subtracting one digit numbers from two digit numbers beginning with one (ten to nineteen). There are 100 problems. The students must be able to do all 100 correctly in ten minutes; only then can they go to the next level--subtracting one-digit numbers from 20 through 29.
例如：在二位數減一位數的練習中，光是一字頭的二位數（十一至十九）減個位數字就是一級，練習題翻來歷去地共有一百題，學生必須在十分鐘之內答對所有題目，才能晉一級﹘ ﹘廿至廿九減個位數字。