The rectangular prism is made up of the dimensions
Lenght = 4 cubes
Width = 2 cubes
Height = 4 cubes
The total number of cubes she needs shall be derived as number of cubes along the lenght multiplied by number of cubes along the width, and then multiplied by number of cubes along the height. Therefore, she would have:
Therefore, She need 32 cubes to make the prism.