Question

a brick measures 30cm long, 10cm wide&7.5cm in height 30×10×7.5 how many bricks will be required for a wall 30m long, 2m height & 3/4 m tgick

Answer 1

volume of 1 brick = 30×10×7.5 = 2250 cm3

volume of wall = 30×2×(3/4) m3 = 45 m3

45m3 = 45 × 10^6 cm3

$no. \: of \: bricks \: required = \frac{45 \times {10}^{6} }{2250} = 20000$

Hence 20000 bricks would be required to build the wall.

Answer 2

In this case,
No. of bricks = Volume of wall / Volume of one brick
i.e. (0.3*0.1*0.075)/(30*2*0.75) = (30*2*75*10*10*1000) /(3*1*75*100) =20000.