If 82° 30' east longitude (Allahabad) shows 6:00 a.m. ofSunday (local time), then local time of Florida (USA) located on 82° west longitude will have 6:58 pm of Saturday. The earth has 360 imaginary lines called longitudes or meridians running vertically between the poles. Each of these longitudes is called a degree. The time difference between each longitude (each degree) is 4 minutes. To calculate difference first, we need to know what longitude the two places are located in. Next, we would need to find the differences in longitude (in degrees) between the two places. If both the places are located on the same side of the Prime Meridian, then the numbers are just simply subtracted to find the difference. If they are on the opposite side of the Prime Meridian, then the two numbers should be added together to find the difference.