Significant Figures by Example

 
39454
5 significant figures
 
3.495
4 significant figures
 
0.486
3 significant figures
 
0.00486 or 4.86 * 10^-3 or 486 * 10^-5
3 significant figures
 
12.3 * 10^3
3 significant figures
 
12.300 * 10^3
5 significant figures
 
12300
We don’t know (could be 3, 4, or 5)
 
Round to 3 significant figures: 2.4984 or 2.4964
Ans: 2.50
 
Round to 3 significant figures: 2.4854 or 2.4754
Ans: 2.48