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But, the International Convention on time zones dictates that the standard meridian of a country be a multiple of 7.5 degrees, so that there is a difference of multiples of 30 minutes (7.5 × 4 minutes per degree = 30 minutes) between time zones. As you can see from the map, the convention means Nepal’s standard time zone should be the same as India’s.
However, Nepal is one of the two exceptions to this convention, as it adopted in 1956. The 82.5 degree longitude divides Nepal into two very unequal parts, with the western portion covering a very small area. So it was decided that Nepal’s Standard Meridian should pass through Mount Gauri Shankar (86°20′ E), which lies 100 km east to Kathmandu. This is not a multiple of 7.5 degrees, and gives a standard time zone of approximately GMT+05:45, which is approximated to GMT+05:45.
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