question_answer 4)

                Parikshit makes a cuboid of plasticine of sides 5 cm, 2 cm, 5 cm. How many such cuboids will he need to form a cube?

Answer:

                Volume of a cuboid \[=5\times 2\times 5\,\,c{{m}^{3}}\]. Since there is only one 2 and only two 5 in the prime factorisation, so, we need \[2\times 2\times 5,\] i.e., 20 to make a perfect cube. Therefore, we need 20 such cuboids to make a cube. The cube root is the inverse operation of finding cube.