How many 1-inch cubes do you need to create a cube with an edge length of 5 inches?

Number of 1 inch cubes:

Volume of the 1 inch cubes = 1*1*1 = 1 cubic inches.

Volume of the 5 inch cubes =  5*5*5 = 125 cubic inches.

Number =  Volume of the 5 inch cubes / Volume of the 1 inch cubes

            =  125 /1 = 125.

125 of the 1-inch cubes.