Problem Post 2-6: How Many Shapes, Part 3: Rectangles in Not-Rectangles

		Problem Posts
		Part 3 of 4 of How Many Shapes?

[Level 2-3]

While it would be far more fun for me if I jumped from topic to topic, I believe I owe it to you, dear readers, to flog this horse until it's brain dead. Completeness is a virtue.

So last time we finished off the case where we count rectangles in rectangles, even when some 'matchsticks' or grid wires are missing. Now onwards to rectangles in non-rectangles.

CAN WE DO BETTER?

• What if the original grid were a rectangle, instead of a square? Or an irregular figure?
• What if we were counting rectangles instead of squares?
• What if some of the grid 'wires' are missing?
• What if we're working on a triangular grid, counting triangles? Does our logic still apply?

2 Rectangles in Non-Rectangles

This is ad hoc land. The base technique would again be to count one-by-one, but as we will see there are tricks for certain special irregular figures.

Problem Post 2-5: How many Shapes, Part 2: Rectangles in Rectangles

		Problem Posts
		Part 2 of 4 of How Many Shapes?

[Level 2-3]

So in my previous Miscellaneous post, we solved a fairly simple Internet puzzle, counting the number of squares in a square grid. But now, we ask ourselves if we can do more:

CAN WE DO BETTER?

• What if the original grid were a rectangle, instead of a square? Or an irregular figure?
• What if we were counting rectangles instead of squares?
• What if some of the grid 'wires' are missing?
• What if we're working on a triangular grid, counting triangles? Does our logic still apply?

Problem Post 2-4: On the Escalation of P*cking Problems

Problem Posts

Image Credit: "Cardboard Box City" by James Nash. Licensed under CC BY-NC-SA 2.0.

No, I don't think they'll make you solve this problem in fifteen seconds mentally.

[Level 1]

\( \def \cm{\rm{\,cm}} \def \mtr{\rm{\,m}} \)

You may wonder why I used the P-word for something as "simple" as packing boxes. I mean, the question is straightforward... right?

THE PROBLEM
You have a big rectangular pallet upon which you must place identical rectangular boxes. You can't stack, collapse, or overlap boxes. The sides of the boxes have to parallel to one of the sides of the pallet. What's the maximum number of boxes you can place?

It's a familiar but unremarkable question, especially for many mathletes who've had to do it under time pressure. (Fifteen seconds mental? Easy!) And the real-life applications are obvious - putting things into shipping containers, for example.