kWhr is calculated by taking the wattage of the appliance in question, multiplying it by how many hours it's on, then dividing by 1000. So, for example, if you leave a fan on all month and it...
Their are many ways to calculate the things in right way. Try to use calculator or some kind of small paper in your hand if you need to calculate things in hurry.
There is a long and complicated way to do it, but there is another simpler way called successive aproximation. To find the square root (S) of X, the equation is S2=X. Make a guess for S, call your...