The metric prefix "atto-" makes a measurement how much smaller than the base unit?

The metric prefix "atto" denotes a measurement that is one quintillionth (10^-18) of the base unit. This prefix signifies an incredibly small value relative to the base unit, making the measurement significantly smaller. For example, if we consider the meter as the base unit, the attometer would be one quintillionth of a meter, or 0.000000000000000001 meters.