Question

what is the difference between Indian standard time and Greenwich mean time?

Answer 1

Greenwich time is the time in London, ist is indian time. GMT is at 0degrees. IST is at 821/2 degrees, I.e 5.30 hours ahead...

Answer 2

IST is ahead of GMt by 5 hours and 30 minutes. Add 1 hour for every 15 degrees of Longitude to the east of Greenwich, London and reduce 1 hour for every 15 degrees to the west of that line. IST is for Kolkata and is valid through out India