Nope. Ans is 4780

Number of cubes=60x12x30 =21600 Number of cubes that DO NOT touch the box= (60-2)x(12-2)x(30-1) =16820 Number of cubes that touch the box= 21600-16820 =4780.

Can explain (30-1)

30 is the height. Notice the container is open, so I only minus 1 (bottom layer). The top layer is not touching the box anyways.

Thanks much.!

Okay! Understand all my working?

Yes.

Sorry. (60-2) alr why still need (12-2) ?

For both length an breadth, the two extreme rows of cubes are touching the sides of the box. So you need to minus 2 for both length and breadth

Then isn't it 58 X 10 there will b hollow at 4 corners

What do you mean by hollow...? 😳

Oh I think I got it now.

Thanks.

60-2 : for each horizontal layer of cubes, the 2 extreme rows of cubes touch the inside of the box. Thus, the horizontal count (for length) of cubes in each horizontal layer that DOES NOT touch the box is 58.

12 - 2 : looking from the side of the box, the two extreme rows of each layer of cubes is also touchin the box. Hence, the number of cubes (breadth) is 10.

30 - 1: for each vertical column of cubes, only the bottom cube is touching the side of the box. Hence, vertical count of cubes (height) is 29.

The model method is not necessary here. Since the number is between 40 and 60, we look at multiples of 8 close to 40 (e.g. 32, 40, etc). There are only 2 numbers which are multiples of 8 plus 5 -- 45 (40 + 5) and 53 (48 + 5). Of these two numbers, only 45 is also a multiple of 6 plus 3 (42 + 3).

Thanks. I was just thinking whether any Model Method in case of similar questions with bigger numbers which will take longer time to solve. I agree in this case, it can be solved without it.

If the numbers are bigger, you can always start from a bigger multiple.

Teck Kwee, u might use the method if the number is huge, say between 8006 and 8026.

Angle CDG = 60 - 45 = 15; Angle DFC = 180 -15 - 60 = 105; Angle EFG = DFC = 105.

105

Why is Angle CDG=60 -45?

Because, angle BDG=60 and angle BDC=45 (the working on the paper shows that the child understands that the diagonal forms 45 deg with the side of the square).

Ahhhhhh...I did not see that. Now I understand. Thank you very much.

Thanks