在生产、科研、教学等工作岗位上,经常要遇到多位数的平方或立方,在身边既无数学用表又无计算机(尺)的情况下,介绍一种迅速而准确的速算法。1.两位数平方(1)原理:设任意两位数平方为(ab)~2,根据笔算法为(a~2 2ab b~2)(见图1)。可以总结出以下规律:两位数平方答数的个位数必为b~2的末位,b~2的十位数应进位到前位;答数的十位数必为2ab+进位所得和的末位,其余的也进位到前两位数的平方可能是三位数或四位数,故百位或千位数必为a~2+进位。即(ab)~2= In production, scientific research, teaching and other work positions, often encounter multi-digit square or cubic, in the side of neither mathematics table and no computer (ruler) case, the introduction of a fast and accurate speed algorithm. 1. Two-digit square (1) Principle: Let arbitrary two-digit square (ab) ~ 2, according to pen algorithm (a ~ 2 2ab b ~ 2) (see Figure 1). The following rules can be summed up: The unit digit of the two-digit square answer must be the last digit of b ~ 2, the ten digit of b ~ 2 should be carried to the first digit; the tens digit of the answer number must be 2ab + Of the last bit, and the rest are also carried into the first two digits of the square may be three or four digits, so a hundred or thousand digits will be a ~ 2 + carry. Ie (ab) ~ 2 =