How must unit cubes be stacked when used to measure volume?

in a solid mass closely fitting the shape. (no gaps)

Three

12 twelve

Unit cubes are used to measure volume by stacking them to fill the given space. To determine how many unit cubes are needed, follow these steps:

1. Start by visualizing the shape or object whose volume you want to measure. For example, let's say you want to measure the volume of a rectangular box.

2. Divide the shape or object into smaller sections or layers, such as one layer at a time. This will help in counting the number of unit cubes needed.

3. Begin stacking the unit cubes, one on top of the other, following the length, width, and height of the shape. Each cube should be placed directly on top of the previous one, without any gaps or overlaps.

4. Keep adding cubes until the entire volume of the shape is covered or filled. Ensure that the cubes are aligned neatly with each other and fill the space completely.

5. Count the total number of unit cubes used. This will give you the volume of the shape in terms of the number of unit cubes.

Note: For irregular or more complex shapes, it may be helpful to break them down into smaller, simpler shapes and add up their volumes to find the total volume.