Question: is pico smaller than nano?
Answer: A kilogram being a thousand grams, but a nanogram isn't a billionth of a gram, it's just a millionth, it's a billionth of a kilogram. Anyway, smaller than nano? ... pico (million-millionth), femto (million-billionth), atto (billion-billionth), zepto (billion-trillionth), yocto (trillion-trillionth).