Ratios

A pancake recipe calls for 3 cups of flour and 2 cups of milk. That '3 to 2' isn't a measurement of anything by itself — it's a relationship between two quantities. Double the recipe and you need 6 cups of flour and 4 cups of milk, but the relationship '3 of flour for every 2 of milk' never changes. That portable, scalable comparison is a ratio, and it's quietly running recipes, maps, paint mixes, and engine fuel everywhere.