how many unit cubes are in one layer? unit cubes in one layer

Explanation:

Step1: Count rows and columns

Count the number of unit - cubes in rows and columns of one layer. Assume the layer has $m$ rows and $n$ columns.

Step2: Calculate number of unit - cubes

The number of unit - cubes in one layer is the product of the number of rows and columns, i.e., $m\times n$. From the image, if we assume the layer has 4 rows and 3 columns, then the number of unit - cubes in one layer is $4\times3 = 12$.

Answer:

12