Remember the rules for significant figures:
- Non zero digits are alw significant
- Any zeros between 2 non zeros are alw significant
- Behind the decimal point
- significant numbers start from the first non zero number
- zeros behind that non zero number are significant
- zeros before that non zero number are NOT significant

e.g. 0.0*500*
only the 500 part is significant, so 0.0500 has 3 significant figures

Hope this helps!