Question

PLEASE EXPLAIN HOW WE FIND CUBOIDS
theses are the answers my teacher gave but i cud not understand

Answer 1

1) you are given two cuboids of dimensions :  5 cm, 2 cm, 5 cm.

you need to make a cube from these cuboids.  That means you have to arrange these cuboids one beside another to make a cube... with equal length, width and height.
 
 Remember the games played with building blocks in childhood?

Take LCM of the length, breadth and height.  so 10 cm is LCM.
So the cube will have 10 cm X 10 cm X 10 cm dimensions.

  So you need 2 cuboids along length,  5 cuboids along width and 2 cuboids one over another to make 10 cm.

So the answer = 2 * 5 * 2 = 20 cuboids you need.

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To make a cube with cuboids of dimensions : 5 cm X 4 cm X 10 cm.

Follow the above procedure.

LCM = 20 cm

so you need:  20/5   X   20/4    X  20/10    cuboids

so    4 X  5  X  2    = 40 cuboids.