# How to Solve a 4th Order Smart Grid (KenKen Sudoku)

Type: 4th Order Smart Grid (KenKen Sudoku)

Smart grid (KenKen Sudoku)

A parent asked Topgames for advice because their child is not good at mental arithmetic. Dou Ba will introduce KenKen Sudoku and problem-solving methods below. If the child can practice every day, it will help to improve their mental arithmetic ability while having fun.

Smart grid, also known as KenKen Sudoku, is actually a type of puzzle. Let’s take a look at the example below.

Rules

Fill in the numbers in the blank spaces (note: for the 3rd order, fill in 1-3, for the 4th order, fill in 1-4, for the 6th order, fill in 1-6, etc.), satisfying two conditions:

1. There should be no repeated numbers in each row and column;

2. The prompt number and operator in the upper left corner of the bold black-lined box indicate that the numbers in the box are obtained by this operation to get the prompted number.

**Analysis of the rules: **As we can see, KenKen Sudoku does not have the concept of palace. It only requires that rows and columns have non-repeating numbers and, at the same time, satisfy the operation requirements. For example, when two boxes have the prompt number “+” 5, it means that the numbers in these two boxes add up to 5.

Playing KenKen Sudoku can be a fun way to practice addition, subtraction, multiplication, and division, making it very suitable for primary school students to learn mental arithmetic skills in an enjoyable way. It not only exercises mental arithmetic skills but also improves logical reasoning ability, observation ability, and concentration, killing two birds with one stone!

The following is a 4th order KenKen Sudoku. Please do not look at the analysis below, challenge yourself first, and then look at the analysis to compare the problem-solving methods (the problem-solving methods are not unique, for reference only). Please note that for the 4th order KenKen, only fill in 1-4.

1

First, check for any gift boxes and fill them in, as shown in the figure below:

2

The second step is to fill in the unique combinations, as shown in the figure below:

3

C line is unique(rest of the candidates), C3 can be determined as 1, and B3 can be obtained from the subtraction and addition. Please think carefully about it.

4

Next, use the 1s in column 3 to eliminate candidates in row D, and D4 can be determined as 1, and D3 can be determined as 3. Then, only 1 is left in column 3, and A3=2.

5

In the fifth step, use the 13 in column 1 to eliminate candidates in row C to obtain C2=3 and C1=2. Then, use C2=2 to eliminate candidates in row D to obtain D1 and D2.

6

In the last step, it is not difficult to use the last elimination and unique relations to solve the problem!

Summary

The methods used in this problem are mainly: unique combinations, elimination, unique solutions, sum and difference methods. Did you answer correctly?