说明：  有乘法算式如下： ○○○ × ○○ ------------ ○○○○ ○○○○ ------------ ○○○○○ 18个○的位置上全部是素数(1、3、5或7)，请还原此算式。 *问题分析与算法设计 问题中虽然有18数位，但只要确定乘数和被乘数后经过计算 就可确定其它的数位。
(multiplication formula is as follows : 2000 2000------ 2000 2000------ 2000 18 hours position all prime numbers (1, 3, 5 or 7), this reduction formula.* Analysis and design of algorithms Although the number of 18-bit, but as long as the multiplicand and multiplier determined after a calculation can be determined by several other.)