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PostPosted: Wed Apr 24, 2013 3:54 pm 
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Joined: Fri Feb 18, 2011 1:45 pm
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A set of 5 squared boxes are made from centimetre cubes and each box fits exactly inside each other, with the tops level. The dimensions of the largest box is 14cm X 14cm X 13cm

c) How many cubes are used to make the third box



The dimensions of the third box would be 10cm X 10cm X 11cm


On face 1(F1), total number of cubes = 10 * 11 = 110
On the opposite face of F1, total number of cubes = 10 * 11 = 110
On the adjacent face of F1 = F1A, total number of cubes = (10 -2) * 11 = 88
On the opposite face of F1A, total number of cubes =(10 -2) * 11 = 88
On the bottom of the cube, total number of cubes = (10 -2) *(10 -2) = 64

So, total number of cubes will be: 460

Am I correct? Is there any other easy way to explain this to a child?

Thanks...


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PostPosted: Wed Apr 24, 2013 5:16 pm 
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Joined: Fri Nov 17, 2006 8:54 pm
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Location: caversham
Work out the volume of the third box and subtract the volume of the fourth box? Less calculations so less errors.


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PostPosted: Wed Apr 24, 2013 5:20 pm 
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Location: caversham
(10*10*11) - (8*8*10)

1100 - 640


460 :D


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PostPosted: Wed Apr 24, 2013 9:21 pm 
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:) Yes, that is a simple solution, thanks stevew61


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