Erchin, 18a: It implies that, as opposed to Damim ('D'mei Cheifetz Zeh alai'),
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where the article is assessed according to its value at the time of payment,
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Arachim - incorporating all the current cases - are assessed according to their value at the time of the declaration.
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Erchin, Ibid.: Even though Damim is compared to Erchin regarding 'Margalis la'Kalim' and 'Ladun bi'Chevodo' - See Torah Temimah, notes 88 & 89, respectively.
And that is when the full assessment applies. Consequently, "ve'Im Achar ha'Yovel - in Pasuk 18 - must be interpreted as 'Achar Achar' (the year following the year after the Yovel). See Torah Temimah in Pasuk 18, citing Erchin, 24b and note 94.
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How much must the owner actually pay when redeeming his field?
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Sifra: Forty-nine Sela'im and forty-nine Pundiyonim
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(one Pundiyon extra)
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for the forty-nine years.
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