Concept: Centreline method: Centreline method is easy and quick in calculations. In this method sum total length of centre lines of all walls, long and short has to be found out. This method is well suitable for walls of similar cross-sections. In this method, the total centre line multiplied by the breadth and depth of the concerned item gives the total quantity of each item. Calculation: √1.122+22=2.29 Total centre line = 2.29 + 5 + 0.3 + 5 + 0.3 + 5 + 2.29 + 2.5 = 22.68 m