• When Rashi gathers a collection of verses and infers from numerical computations we say Rashi uses the Spreadsheet method.
• The spreadsheet method is also said to be used when Rashi clarifies with a geometric diagram.
• We also say the spreadsheet method is used when Rashi fills-in background with plausible real-world events. Since these fill-ins are not derived from the Biblical text but rather are derived from the real-world we consider them analogous to the use of diagrams and computational spreadsheets. The common denominator of
  • Numerical spreadsheets
  • Geometric diagrams
  • plausible real world fill-ins and backgrounds
  is inference from non-verse material. Todays example particularly illustrates this.

Verse Gn31-15 discussing Jacob's plan to desert his father-in-law states Are we not counted by him as strangers? for he has sold us, and has quite devoured also our money Rashi explains the underlined phrase for he has sold us, by filling in with real-world background: In most marriages the father of the bride provides a monetary dowry to help get the couple started. But in Jacob's marriage the exact opposite happened: Jacob had to pay his father-in-law, by working for him for 7 years. Hence the Biblical phrase he sold us.

To recap, Rashi comments on the verse by
• bringing in the custom of the father of the bride giving a dowry to his future son-in-law
• contrasting the gift of the father-in-law to the son-in-law with the purchase requirement of 7 years of labor to obtain Rachel.
Because this comment uses real-world vs non-textual material we say the spreadsheet method is being used.

Sermonic points: The Rashi teaches us the importance of marriage etiquette. The young couple should be helped out. The father-in-law should treat his future son-in-law nicely. He certainly should treat his own daughter nicely.