Given, sides of a cuboid are 5cm, 2cm and 5cm

Volume of cuboid =5*2*5 = 50 cm³ 

Let the side of the cube formed with minimum number of cuboids = x

Hence volume of the cube = x³

Number of cuboids required = n

Hence n*50 = x³

Now, n*50 must be perfect cube

n*50 = n*2*5*5

So, minimum value of n = 2*2*5 = 20

Hense, the number of cuboid will be needed to form a cube is 20