Question

the calculator the difference between the local time of any two place on the earth

Answer 1

The earth has been divided into 360 degrees of imaginary longitudinal lines. Now, these 360 degrees divided by the 24 hour day, results in 4 minutes per longitude. Thus, if you move from one longitude to the next the difference will be of 4 minutes. 360 degree = 24 hours, so 1 hr = 15 degrees, 1 degree = 4 minutes.