初二的数学计算题,常常会涉及到求一个数的平方值。对于求20以内自然数的平方值,我们一般都能马上写出结果。因为小学时,老师就要求我们把20以内的平方值列一个表,并将它背熟。但遇到大于20的自然数时,我们就只能按乘法法则的步骤在草稿纸上用竖式演算。这时,往往因数值比较大,一不小心就会 The mathematics problem of the second grade usually involves the square value of a number. For the square of the natural number within 20, we can usually write the result immediately. Because at the time of elementary school, the teacher asked us to list a square value within 20 squares and memorize it. But when we encounter a natural number greater than 20, we can only use vertical steps on the draft paper in accordance with the multiplication rule. At this time, it is often due to a large number of values.