We learned in grammar school how to multiply two-digit numbers with pencil and paper, but I’ve never heard this phrase, which metaphorically substitutes the placement for the arithmetical operation. In this passage from Joe Turner’s Come and Gone, set in 1911, pedlar Selig is buying finished cookpots from artisan Seth at a dollar apiece, who is in turn buying raw materials (eight sheets of metal) from Selig:
SELIG: How many of them pots you got?
SETH: I got six. That’s six dollars minus eight on top of fifteen for the sheet metal come to a dollar twenty out of the six dollars leave me four dollars and eighty cents.
SELIG (Counting out the money): There’s four dollars… and… eighty cents.
—August Wilson, Joe Turner’s Come and Gone, I:1
Or (6 · 1) – (8 · 0.15 ) = 4.80.