Why is converting Eratosthenes' final calculated circumference (252,000 stadia) into modern kilometers subject to scholarly debate?

Answer

The exact length of the *stadion* unit varied geographically and temporally.

The final conversion into kilometers is uncertain because the precise length of the stadium unit used by Eratosthenes differed depending on the specific regional standards employed at that time.

Why is converting Eratosthenes' final calculated circumference (252,000 stadia) into modern kilometers subject to scholarly debate?
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