Avraham paid 400 shekels for the Me’aras Hamachpela [Bereishis 23:16]. However, these were especially valuable shekels called centenaria. Each of these special shekels was worth 2,500 normal shekels [Bava Metzia 87a].
Question: What was the value of the payment made by Avraham in normal shekels?
Answer: 2,500 x 400 = 1,000,000
