Again this question is also from NCERT Maths books class 10th, chapter 13 mensuration, here a cuboidal box of dimensions 1 m × 2 m × 1.5 m is given to us and it has  to be painted except its bottom. We have to calculate how much area of the box has to be painted. Please help me to solve this question also can some tell me how calculate fast as in these type of questions i face a lot of difficulties in calculations.