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PROJECT EULER · #0147

Rectangles in Cross-hatched Grids

Statement only · SolvedOriginal problem ↗

In a 3×2 cross-hatched grid, a total of 37 different rectangles could be situated within that grid as indicated in the sketch.

There are 5 grids smaller than 3×2, vertical and horizontal dimensions being important, i.e. 1×1, 2×1, 3×1, 1×2 and 2×2. If each of them is cross-hatched, the following number of different rectangles could be situated within those smaller grids:

1×11
2×14
3×18
1×24
2×218

Adding those to the 37 of the 3×2 grid, a total of 72 different rectangles could be situated within 3×2 and smaller grids.

How many different rectangles could be situated within 47×43 and smaller grids?

Write-up coming later

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