Problem number 12, George, that's me, wanted the sum of the three numbers in each row and each column of the grid to be the same. I made one mistake. Which number must I correct? 1, 3, 1 of the 4s, 5, or 1 of the 7s? You're going to look at the sum of each row and column, and then whichever number is in both a row and a column that are different than the others will be the one that we need to change. So at this top row we see that we have 9 and 1, which is 10, and 5, which is 15. Then we have 3, 7, and 6, which is 10 and 16. And then we have 4, 7, 4, which is also 15. And then if we look at this first column, 9 plus 3 is 12, plus 4 is 16. And then 1 plus 7 plus 7 is 15, and 5 plus 6 plus 4 is 15. Now we see that we have two answers which are 16 while all the others are 15. And only one number is in both of them, which is 3, which means we need to change out the number 3. So our answer is B. And all I need to do is make it into a 2 for it to be the same.

grid puzzle

number correction

sum consistency

mistake identification

solve problem