A prefix meaning one-quintillionth (1/1,000,000,000,000,000,000 or 10-18)
The same as multiplying by 10-18 (which is 0.000 000 000 000 000 001)
Prefix is a
Example: 12 am = 12 attometers = 12 quintillionths of a meter (0.000000000000000012 m)
