Finding the Middle Number
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[Originally posted in the Discussions ]
Module 0 Week 2 Day 5 Challenge Explanation Part 2
Why did he draw the two diagonals and the vertical and diagonal lines to find out the middle number? What about the other diagonals and verticals?
Hi Xiao Ma,
That is a good question!
He drew two diagonals, one vertical and one horizontal. He did this because the interesting property of a magic square is that every row, column, and diagonal have numbers that add up to the same sum.
Now, there's a special reason why he chose to draw the middle vertical line, and not the one on the left (with the 8 in it). It's because he wanted to cover every single number in the magic square. Since the diagonals already include the corner squares, he intentionally chose the vertical and horizontal to cover different squares. This works quite well, since every number is counted once, except for the center. The center is counted in each line, so it is counted four times. But in our case, that was on purpose, so that we could figure out how much bigger the sum of the numbers in the four lines is, compared to (1 + 2 + 3 + 4 + 5 + 7 + 8 + 9).
Neat trick, huh?
I think it's awesome that you're asking these questions, because it means that you're not just passively listening along; you're actively thinking as well. This way, you will learn surely learn a lot.
Happy Learning,
The Daily Challenge Team
