Volume of cuboid = lbh,
where, l = length, b = breadth and h = height
For wall,
Length, l = 24 m
Breadth, b = 0.4 m
Height, h = 6 cm
Volume of wall = 24(0.4)(6) = 57.6 m3
As of this volume is covered by mortar, therefore of this volume is covered by bricks
For one brick,
Length, l = 25 cm = 0.25 m
[As 1 m = 100 cm]
Breadth, b = 16 cm = 0.16 m
Height, h = 10 cm = 0.10 m
Volume of one brick = lbh = 0.25(0.16)(0.10) m3
Hence Total No of bricks used in constructing the wall is 12960.