How do you determine the number of significant figures in a problem?
As a general rule, use the least number of significant figures present in the given problem/data. More rules follow.
Your answer can only be as precise as the least precise measurement!
1. Least number of significant figures present in given data
For example, if the problem states that there is 20.0 mL of a 0.10 M Na(OH) solution, your final answer would have 2 significant figures because 20.0 has 3 sig figs and 0.10 only has 2.
2. When adding/subtracting
Use the least number of significant figures past the decimal point when adding or subtracting numbers. For example, the answer to 123.45 + 543.2 would have 1 significant figure past the decimal point.
3. When multiplying/dividing
Use the least number of significant figures present in any number in the problem when multiplying or dividing numbers. For example, the answer to 2.3 x 5.32 would have 2 significant figures in the entire number.