Question

count the number of cubes used to build each three - dimensional figure.
1.
2.
3.
18 unit cubes
unit cubes
unit cubes
4.
5.
6.
unit cubes
unit cubes
unit cubes

Explanation:

Step1: Count layers and cubes per layer

For the first figure, assume length = 6, width = 3, height = 1. Number of cubes = length×width×height = 6×3×1 = 18.

Step2: Analyze second figure

For the second figure, length = 5, width = 4, height = 1. Number of cubes = 5×4×1 = 20.

Step3: Analyze third figure

For the third figure, length = 3, width = 3, height = 2. Number of cubes = 3×3×2 = 18.

Step4: Analyze fourth figure

Count layer - by - layer. Bottom layer has 8 cubes, top layer has 4 cubes. Total = 8 + 4 = 12.

Step5: Analyze fifth figure

Bottom layer has 6 cubes, middle layer has 3 cubes, top layer has 1 cube. Total = 6+3 + 1=10.

Step6: Analyze sixth figure

Bottom layer has 6 cubes, top layer has 1 cube. Total = 6 + 1 = 7.

Answer:

1. 20 unit cubes
2. 18 unit cubes
3. 12 unit cubes
4. 10 unit cubes
5. 7 unit cubes