1-6 Precision and significant figures (有效数字) The number of significant figures tells us the precision of the measuring result There are a few simple rules to follow in deciding how many significant figures to keep Rule 1. X=3.0m and X=0.0030km imply that we know the value of to be two significant figures Be careful about ambiguous notations: X=300m1-6 Precision and significant figures (有效数字) • The number of significant figures tells us the precision of the measuring result. • There are a few simple rules to follow in deciding how many significant figures to keep: Rule 1. x=3.0m and x=0.0030km imply that we know the value of x to be two significant figures. Be careful about ambiguous notations: x=300m