[alexander_busek]

The irony is the 500 has ONE significant figure, therefore the answer cannot have more than one significant figure.

You may be right in this particular case - but a zero is not automatically a non-significant figure. Any given zero need not be the result of rounding; ratehr, it could be the result of an actual measurement.

Regards,

[ProtectOurFreedom]

Significant Figure Rules

There are three rules on determining how many significant figures are in a number:

1. Non-zero digits are always significant.
2. Any zeros between two significant digits are significant.
3. A final zero or trailing zeros in the decimal portion ONLY are significant.