Question

Parikshit makes a cuboid of plastic of side 5 cm x 2 cm x 5 cm. How many such cuboids will he need to form a cube

Answer 1

Volume of cube of sides 5 cm, 2 cm, 5 cm =$5cm\times 2cm\times 5cm=(5\times 5\times 2)c{m}^3$
Here, two 5s and one 2 are left which do not form a triplet.
To make it a pefect cube, multiply this expression by $2\times 2\times 5=20$,then it will become a perfect cube.
i.e. $(5\times 5\times 2\times 2\times 2\times 5)=(5\times 5\times 5\times 2\times 2\times 2)=1000$ is a perfect cube.
Therefore 20 cuboids of 5 cm, 2 cm, 5 cm are required to form a cube.