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How the math works
Each line is scanned for numbers (including fractions like "1 1/2" and unicode ½) and the first numeric value is multiplied by the target/original ratio. Common units (cup, tbsp, tsp, g, kg, ml, oz, lb) are detected so non-quantity numbers (oven °F, minutes) stay untouched.
Results are rounded to friendly fractions (¼, ⅓, ½, ⅔, ¾) when below 10 cups/tbsp/tsp, and to whole grams above. The metric toggle converts cups (×240 ml), tbsp (×15 ml), tsp (×5 ml), oz (×28 g), lb (×454 g), °F → °C.