Question

How many significant figures are in the measurement 0.0105 km?

Answer 1

`3`

Explanation:

The first and most important thing to notice here is that your measurement contains two non-zero digits, `1` and `5`.

As you know, all non-zero digits are significant, so right from the start you know that your measurement contains at least two significant figures

`0.0color(purple)(1)0color(purple)(5) ->` two non-zero digits

Now, the zero that precedes the decimal point is not significant because it acts as a placeholder zero for a number that is smaller than `1`.

The same can be said for the zero that follows the decimal point. Once again, this zero is not significant because the number is smaller than `1`.

Finally, the zero that follows `1` and precedes `5` is a sandwiched zero, which basically means that it is being flanked by two non-zero digits.

All sandwiched zeroes are significant, which means that your measurement has a total of three significant figures, two non-zero digits and a sandwiched zero.

`color(red)(0).color(red)(0)color(purple)(1)color(darkgreen)(0)color(purple)(5) ->` three sig figs