Grades 3-4 Video Solutions 2012-2012_3-4

Video Transcription

Problem number 12. In a Sudoku puzzle, the numbers 1, 2, 3, 4 can only occur once in each column and in each row.  In the mathematical Sudoku to the left, Patrick first writes the results of the calculations. Then he completes the Sudoku. Which number will Patrick put in the gray cell?  A1, B2, C3, D4, or E1 or E2. And also the Sudoku is on the bottom. To do a Sudoku, do a row or column where there is only one number missing.  We are going to start on the second row. So we see that 2 times 2 is 4, 6 minus 3 is 3, and 6 minus 5 is 1.  This leaves us with only one possible number left in this row, which is 2. On the third row, 4 minus 1 is 3, and 1 plus 3 is 4, and 8 minus 7 is 1.  Which again, the only number possible is 2. In order to complete the gray cell, we have to find the number that goes in the upper right hand corner.  So in order to do that, we need to solve the first row. In order to solve this row, we need to do the second column.  Starting with the row, 1 times 1 is 1, and now we are going to go down here. Where 2 minus 1 is 1, the second number in the first row is 2, and then 1 times 3 is 3.  So the only remaining number for the top row is 4. Now we see we have 4, 1, 2, which means the only possible number to go here is 3. Which means our answer is C, 3.

Video Summary

In a given Sudoku puzzle, you must fill each number from 1 to 4 only once in each row and column. To solve which number belongs in the gray cell, the puzzle requires completing the second row showing results of operations (2 and 1 columns need a 2). Once each potential row and column are solved as per remaining numbers, for the first row, missing numbers reveal that the only number to finalize the position in the upper right corner is 3. Thus, Patrick places 3 in the gray cell, making the correct answer C, 3.

Keywords

Sudoku

puzzle

numbers

row

column