By counting carefully it can be seen that a rectangular grid measuring 3 by 2 contains eighteen rectangles:
Although there exists no rectangular grid that contains exactly two million rectangles, find the area of the grid with the nearest solution.
This problem looks more difficult than it is, I’m not going to go into the details here but basically the number of rectangles inside a x by y grid can be calculated as:
The rest is fairly easy, just pick a range of x and y values you want to try and brute force it!
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