# Try to guess the number of cubes in the following arrangements (Fig 15.17).

G Gautam harsolia

i) There are 4 columns and 2 rows in the first line.
So, the total  number of cubes in the first line is
$\Rightarrow 4 \times 2 = 8$
And there is total 3 such line.
Therefore, the total number of cubes are $\Rightarrow 8\times 3 = 24$

ii) There are 3 columns and 1 row in the first line at the bottom.
So, the total number of cubes in the first line are
$\Rightarrow 3 \times 1 = 3$
And there are total 2 such lines
So, the total number of cubes at the bottom are $\Rightarrow 3 \times 2 = 6$
Now, we can see that two cubes are placed on the second line
Therefore, the total number of cubes are $\Rightarrow 6+2=8$

iii)   There are 3 columns and 1 row in the first line at the bottom.
So, the total number of cubes in the first line are
$\Rightarrow 3 \times 1 = 3$
And there are total 2 such lines
So, the total number of cubes at the bottom are $\Rightarrow 3 \times 2 = 6$
Now, we can see that two cubes are placed on the second line  and one cube in the front of the first line
Therefore, the total number of cubes are $\Rightarrow 6+3=9$

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