How small is a billionth?

Answer 1

Mathematicians, engineers and scientists avoid the words billion and billionth because they have different meanings in different countries.

e.g. one billion (US) 109. one billion (UK) 1012.

So, mathematicians use exponents as shown above.

Engineers and scientists mostly use SI multipliers.

106 = Mega, 109 = Giga, 1012 = Tera

10-6 = micro, 10-9 = nano, 10-12 = pico.

If you are American, a billionth is 10-9 . If you are a Brit it is 10-12.