A prefix meaning one-septillionth (1/1,000,000,000,000,000,000,000,000 or 10-24)
The same as multiplying by 10-24 (which is 0.000 000 000 000 000 000 000 001)
Prefix is y
Example: 12 yg = 12 yoctograms = 0.000 000 000 000 000 000 000 012 g
The rest mass of a proton is 1.6726 yg
