Question

Which number has one significant figure: `4xx10^(-23)` or `4.0xx10^(-23)`?

Answer 1

It would be `4xx10^(-23)`. `4.0xx10^(-23)` would have two sig figs.

Answer 2

the correct answer is `4xx10^(-23)`

Explanation:

`4xx10^(-23)` is one significant figure.

`4.0xx10^(-23)` is two significant figures since it contains a trailing zero in a number that has a decimal point.

Here is a full explanation on significant figures:

Source: Screenshot from my teaching notes.