Multiplying double and triple ratios
"Multiply a double by a triple, it makes 6"
A pencil note headed "Difinizione" (Definition) works through the multiplication of ratios, with the rule "Multiplica una dupla vie una tripla, fa 6" (multiply a double by a triple, it makes 6). Columns of the numbers 8, 4, 2 are labelled dupla (double) and quadrupla (quadruple), and a further step instructs to "multiply the denominator." The figures are faint and the layout schematic, arranging values to show how proportions combine.
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Double, triple and quadruple ratios combined
The rule "Multiply a double by a triple, it makes 6" is set beside a descending column 8, 4, 2 that is bracketed and labelled dupla (double) and quadrupla (quadruple). A second working directs the reader to "multiply the denominator," reducing paired numbers such as 3 and 9. Together the notes treat ratios as quantities that can be multiplied one by another.