Shortcut Trick
Convert all dimensions to cm: Wall = 1800 × 1000 × 40 | Brick = 30 × 15 × 10
Number of bricks = (1800 × 1000 × 40) ÷ (30 × 15 × 10)
Number of bricks = 60 × 66.67 × 4 = 16000 bricks
Required answer in thousands = 16000 ÷ 1000 = 16
∴ The correct answer is 16.
Alternate Method
Given:
Length of wall (L) = 18 m = 1800 cm
Height of wall (H) = 10 m = 1000 cm
Width of wall (W) = 40 cm
Brick dimensions = 30 cm × 15 cm × 10 cm
Formula Used:
Volume of Cuboid = Length × Width × Height
Number of Bricks = Volume of Wall ÷ Volume of 1 Brick
Calculations:
⇒ Volume of Wall = 1800 × 1000 × 40 = 72,000,000 cm3
⇒ Volume of 1 Brick = 30 × 15 × 10 = 4,500 cm3
⇒ Total Bricks = 72,000,000 ÷ 4,500
⇒ Total Bricks = 16,000
⇒ Bricks in thousands = 16,000 ÷ 1000 = 16
∴ The correct answer is 16.
Additional Information
Unit Consistency
Always ensure all dimensions (Length, Width, Height) are in the same unit (cm or m) before calculating volume. 1 m = 100 cm.
Volume of a Cuboid
The amount of space occupied by a 3D rectangular object is given by V = l × b × h.
Number of Items
When a larger object is formed by smaller identical objects, the total number = (Total Volume) ÷ (Volume of one small item).