Packing Intuition Examples in Math

Start with the recap, study the fully worked examples, then use the practice problems to check your understanding of Packing Intuition.

This page combines explanation, solved examples, and follow-up practice so you can move from recognition to confident problem-solving in Math.

Concept Recap

Arranging objects of given shapes to fit as many as possible into a bounded region without any overlapping.

How many oranges can you stack in a box? How to arrange them?

Read the full concept explanation โ†’

How to Use These Examples

  • Read the first worked example with the solution open so the structure is clear.
  • Try the practice problems before revealing each solution.
  • Use the related concepts and background knowledge badges if you feel stuck.

What to Focus On

Core idea: Optimal packing efficiency depends heavily on shapeโ€”circles leave gaps that squares would fill.

Common stuck point: Optimal packing problems are often surprisingly hard to proveโ€”even for simple shapes like circles.

Sense of Study hint: Try arranging coins in a square grid, then shift every other row to make a honeycomb pattern. Count how many fit each way.

Worked Examples

Example 1

easy
Circular coins of radius 1 cm are packed into a 10\,\text{cm}\times 10\,\text{cm} square tray in a square grid arrangement. How many coins fit and what is the packing efficiency?

Solution

  1. 1
    Step 1: Each coin occupies a 2\,\text{cm}\times 2\,\text{cm} square cell. Number per row = 10/2 = 5. Total coins = 5 \times 5 = 25.
  2. 2
    Step 2: Area of each coin = \pi(1)^2 = \pi cm^2. Total coin area = 25\pi cm^2.
  3. 3
    Step 3: Tray area = 100 cm^2. Packing efficiency = \dfrac{25\pi}{100} = \dfrac{\pi}{4} \approx 78.5\%.

Answer

25 coins; packing efficiency \approx 78.5\%.
Square packing of equal circles achieves efficiency \pi/4 \approx 78.5\%. About 21.5\% of space is wasted as gaps. Hexagonal (honeycomb) packing achieves \approx 90.7\%, which is why beehives use hexagons.

Example 2

medium
Compare the packing efficiency of square packing (\pi/4) vs hexagonal close packing (\pi/(2\sqrt{3})) of unit circles. Which is more efficient and by how much?

Practice Problems

Try these problems on your own first, then open the solution to compare your method.

Example 1

easy
A box is 30 cm long, 20 cm wide, 15 cm tall. How many 5\,\text{cm} cubes can fit inside?

Example 2

hard
Oranges of radius 4 cm are packed in a square grid on a flat tray that is 40\,\text{cm}\times 40\,\text{cm}. A second layer is placed on top in hexagonal arrangement offset by 4 cm in each direction. How many oranges are in the first layer? How many extra fit in the second layer?

Related Concepts

Background Knowledge

These ideas may be useful before you work through the harder examples.

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