Question

How many significant digits does 520 have?

Answer 1

Two significant figures.

Explanation:

Right from the start, you should be able to look at this number and say that it has at least two significant figures given by the two non-zero digits it contains.

Non-zero digits are always significant, so look for them first when trying to figure out how many sig figs you have.

Now, let's focus on that zero.

A zero that follows all non-zero digits and is not followed by any non-zero digits is called a trailing zero. A trailing zero is significant when it follows a decimal point or when a decimal point directly follows it.

In your case, the zero in `520` does not follow a decimal point, and no decimal point directly follows it, therefore it is not significant. You can thus say that the number `520` has two sig figs.

Examples in which that zero would be significant

`52.0 ->` the trailing zero follows a decimal point

`520. ->` the trailing zero is followed directly by a decimal point