A nanometer is one billionth of which unit of measurement?

Intruda, the small fish. I think it may be a pup fish?

Knodel1958, not really. the small fish is a few millimetres long, or a few million nanometres. Light wavelengths and atoms are nanometre scale. Human hair is tens of thousand nanometres. By ten to the minus threes, Milli, micro, nano, Pico, femto, ato.

Knodel1958, whats with the picture lol