Most of the world sets clocks in whole hours from Coordinated Universal Time, but a handful of places use half or quarter hours.
Following the sun
Time zones are meant to keep midday roughly when the sun is highest. A country that sits between two whole-hour zones may choose the halfway point.
One clock for a whole country
India spans nearly 30 degrees of longitude but uses a single time, UTC+5:30, chosen to sit near the middle of the country.
Quarter hours exist too
Nepal uses UTC+5:45, partly to mark its own local solar time rather than follow a neighbour's clock.
The trade-off
One national time is simple for trains and offices, but it means sunrise comes much earlier in the east than in the west.
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