How many bricks 9cmx9cmx18cm need for 1sqfeet?
1 Sq-ft is 929 Sq-cm and the top surface of the brick is 162
Sq-cm. If no space is left between the bricks, it takes 5.73 bricks
per Sq-foot. If a gap is going to be left between the bricks, the
number of bricks per square-foot goes down. With a 1/4-inch gap,
the space occupied by the brick will be about 9.64 by 18.64 cm or
about 5.18 bricks per Sq-foot.