算式Calculation

算式数独有两种类型。Calculation has 2 types.

类型1 算式台 Multiplication Table

标准数独基础上，每个虚线框里上方数字的乘积等于下方的多位数。一般情况下，虚线框的右侧是对齐的。

Classic rules applied. Additionally, in each cages, numbers above product the multi-digit number (with order) below. Generally, the right side of the cage is aligned.

我们网站上绝大多数的算式是这一类。有时我也会使用涂色的区域代替虚线框。

Most of our Calculation is this type. Sometimes, I may use colored zones instead cages. 

◆因数 About the factor

数字1不能作为因数，数字5不能作为最后一位因数。

1 cannot be the factor, 5 cannot be the last factor.

◆奇偶性 Parity

乘积是偶数则一定有偶数的因数，反之亦然。乘积是奇数一定全部是奇数的因数。

Even product must have even factors, vice versa. Odd product must have all odd factors.

定义2 书写算式 Written Multiplication

标准数独基础上，在每个虚线框/涂色区域内，第一行的多位数乘以第二行的数字，最终的多位数等于第三行的多位数。

Classic rules applied. Additionally, in each cages/colored zones, multi-numbers in first row products number in second row, the final product is the multi-digit in the third row.

这种类型出现在2022年波兰的世界数独锦标赛中，被叫做书写算式。

This type appeared in WSC 2022 in Poland, and it was called Written Multiplication.

练习 Practice

① 九阶算式台里有一个2x2的算式，右上角的单元格里不能有______。

There's a 2x2 cage in Calculation Table 9x9, the upper-right corner in this cage cannot be ______.

② 解答问号格 Find out the ？cells.

Answer

① 1 and 5 ② C2=2; B3=6.