Straight back: for example,-one, one, two, until nine, then two, two, four, six, until 298, then three, three, three, nine, three, four, twenty-seven, and so on, followed by four, forty-six, five, five, twenty-five, six, seven, forty-nine, eight, eight.
Cross your back: for example, you run first and come sentence by sentence; The second sentence is two sentences, one sentence is two sentences, and two sentences are four sentences; By analogy, the first few lines are only a few sentences, and the last nine sentences range from 199 to 998 1. There is another rule in this method. In the first few lines, the last sentence is a few more than the previous one.