Because it throws the earth off balance and if it does it often enough then it will soon add up.
Convert all of the units from centimeters to meters by moving the decimal point over to the left two digits.
0.15 m x 0.06 m x 0.12 m
Volume = length x width x height
= 0.15 x 0.06 x 0.12 = 0.00108 m^3
