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珠算能加减能乘除,能乘方,也能开方。但旧的开方法,口诀太多,难懂难学,未被广泛采用。本文所述珠算开平方法,没有什么特别口诀,通俗易学,计算速度很快,比笔算要快得多。珠算开平方的法则和原理系从下面的公式导出来的:(x+y)~2=x~2+2xy+y~2=x~2+(2x+y)·y,式中(x+y)~2称为平方数;(x+y)称为平方根;y是平方根中最后一位数,x是平方根中y以前各位数之和;称(2x+y)为根除数;当求出某一位根时,即从平方数中减去根除数与此位根之积,所得之差则称为剩余数。
Abacus can add, subtract, multiply, multiply, and authorize. However, the old methods of opening up were too many to learn and difficult to learn. They were not widely adopted. The abacus calculation method described in this article has no special vocabulary. It is easy to learn and easy to learn. The calculation speed is very fast and much faster than writing. The principle and principle of a square of abacus is derived from the following formula: (x+y)~2=x~2+2xy+y~2=x~2+(2x+y)y, where (x +y)~2 is called the square number; (x+y) is called the square root; y is the last digit in the square root; x is the sum of the y previous digits in the square root; and (2x+y) is the radical elimination number; When a certain root is found, the product of the root number and the root is subtracted from the square, and the resulting difference is called the remainder.