Question

A cardboard of size 16cm and 24cm has been completely used to from a cube.What will be the size of the cube so formed ?

Answer 1

Surface area of rectangle = l * w = 16 * 24 = 384

Now, Surface area won't change, when it will transform into a cube so, 
6a² = 384
a² = 384/6
a² = 64
a = √64
a = 8

In short, Your Answer would be: 8 cm

Hope this helps!