l= 4.2 m = 4.2 * 100 = 420 cm
b = 1.4 m = 1.4*100 = 140 cm
h =1.2 m =1.2 *100 =120 cm
Volume of cuboid = l*b*h = 420 * 140 * 120 = 705600 cubic cm
Volume of cube = a*a*a = 20*20*20 = 8000 cubic cm
No.of cubes = Volume of cuboid / volume of cube
= 705600 / 8000 = 882 cubes
or 420*140*120 / 20*20*20 = 42*14*12/2*2*2 = 21*7*6 = 882 cubes
