 # Free Electronic Puzzle Games that exercise your mind ready to play online!

Mathematical Mini Sudoku is a reduced variant of Sudoku created by epasatiempos.es and it is played on a 3x3 grid instead of the traditional 9x9. However, and despite the differences, the game has the basic rules that define Sudoku: numbers from 1 to 9 have to be placed into each cell, no two numbers can be the same and there is only one possible solution.

Since the puzzle is so reduced, there are no cells pre-filled for you to help as in traditional Sudoku. There are other kinds of hints instead:

1. On the right of each row and under each column there is a number showing the total sum of the 3 numbers in the corresponding row or column. For example, if the number 16 is on the right of the first row this means that the sum of the numbers in the 3 cells of such row equals 16. The same rule is applied to the rest of rows and columns.
2. On the top of each cell it is indicated whether the number that has to be placed is prime, even or odd. All the cells with prime numbers will indicate so and will be exclusive. This means that the rest of the cells indicating even or odd exclude all prime numbers. Let’s take number 2 as an example. It is prime but it is even, too. The cell to be filled-in with this number will always indicate prime and not even –despite being so. Therefore, we will know that the rest of the cells indicating even will never contain number 2. The same logic is applied to the rest of prime numbers.
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## How to play Mathematical Mini Sudoku

It is very easy. Click on the cells to enter a number. You are only allowed to use numbers from 1 to 9, one for each cell. Any other character will be automatically deleted.

Once you have filled the 9 cells you can click on the Check button that is under the Mini Sudoku grid. This button is used for checking the solution and will show a message whether it is correct or not.

All the numbers will always be logically deducible. It is advisable to write notes down to help you find the solution easily. However, if you are able to solve the puzzle without using pencil and paper it would be better than good!

You can solve so many Mini Sudoku puzzles as you wish by clicking the "Play another Mini-Sudoku" button.

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## How to solve Mathematical Mini Sudoku

Given that all the cells in Mini Sudoku are blank from the beginning, with no helping numbers, the only option to solve it is to consider the possible numbers or candidates that may go into each cell. Then all the rows and columns should be analysed taking into account the sums. After that, the numbers that do not match should be rejected until finding the suitable ones.

The possible candidates according to the hint given in each cell and considering the explanation in the section "About Mathematical Mini Sudoku" go as follows:

1. For cells with prime number: 1. 2, 3, 5 and 7 (the only prime numbers between 1 and 9).
2. For cells with even number: 4, 6 and 8 (number 2 is rejected because it is prime).
3. For cells with odd number: 1 and 9 (numbers 3, 5 and 7 are odd but they are also prime. Remember that being prime is a priority so prime numbers will never go in a box indicating even or odd).

That being said, it is deduced that:

1. Cells with odd numbers will be the ones with less candidates: only two. Therefore, these numbers can be found faster and more easily than the rest.
2. Since odd candidates are only two, there would only be two cells for odd numbers in each Mini Sudoku. This means that if you find one of the numbers you will also find the other one by elimination. For example, if you know that number 1 is the only candidate that matches in a cell, number 9 must go in the other and vice versa.

The next step would be analysing rows and columns whose sum has the lowest value since there will be statistically less possible combinations of three numbers that equal that value. Therefore, it will be easier to find or to reject some of them.

Then add up all the candidates in each row and column to see whether the result matches or not.

See an example of how to solve a Mini Sudoku step by step.
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