Question

5) How many significant figures are in the number 0.122210000?

Answer 1

If it's written just like that, it's `9`

Explanation:

Significant figures are just what they say. `5` has only one, but `5.000` has four.
This is because `5` can be a rounded number from anywhere between `4.5.... and 5.4999...`
While `5.000` is rounded from between `4.995... and 5.00499...`

The zeroes at the front don't count, so `0.0005` still has only one significant digit.