Significant figures | Chemistry and the Scientific Method

State the number of significant figures of the following numbers:

501  

0.0004 

9.00 

5.3 x 108 

0.00700020 

100 

100. 

020.0 

501  ⇒ 3 significant figures

0.0004 ⇒ 1 significant figure

9.00 ⇒ 3 significant figures

5.3 x 108 ⇒ 2 significant figures

0.00700020 ⇒ 6 significant figures

100 ⇒ we cannot tell: it could be 1, 2 or 3 significant figures

100. ⇒ 3 significant figures

020.0 ⇒ 3 significant figures