The number "0.003" is a decimal that represents a very small quantity. It can also be expressed as a fraction, specifically 3/1000. In terms of percentages, "0.003" is equivalent to 0.3%, which means three parts out of a thousand. In practical applications, "0.003" might be used in measurements, such as millimeters or liters, to indicate a precise amount. For example, if a solution contains 0.003 grams of a substance, it signifies a very dilute concentration, often relevant in fields like chemistry or pharmacology.