Verse Lv27-18b discussing the redemption of a field dedicated to the Temple states
But if he sanctify his field after the jubilee, then the priest shall reckon unto him the money according to the years that remain unto the year of jubilee, and an abatement shall be made from thy valuation.
Rashi explains the arithmetic of this redemption process using a proportionate method with rounding.
In presenting the Rashi we supplement his example with extra illustrations to clarify each
component of his comment.
Example 1: Suppose the field I dedicated was evaluated as worth $20. Suppose further
there are 10 years left to the Jubilee. Then each year is assigned a worth of $20/10=$2.
If I wish to redeem the field next year I must pay $18.
If I wish to redeem the field in two years I must pay $16. And so forth. We can summarize this
by saying that we use a proportionate method in redeeming the field.
Example 2: (Rashi)Suppose I dedicate my field right after the jubilee for $50. So the $50
spans 49 years. Suppose further (true in Talmudic times) that each $1 is worth 48 cents.
Then the proportionate method requires that each year be assigned a worth of
$50/49 = $49/49 + $1/49 = $1 + 48/49 cents.
Rashi explains that this is rounded to $1 + 1 cent.
So if the field is redeemed after 10 years the person pays $50 less $10 and 10 cents.
We can summarize this by stating that
redemption uses a proportionate method with rounding.
Because this Rashi clarified biblical content with arithmetic-spreadsheet methods
we classified this Rashi as using the non-verse method.