Chapter 1 Introduction 1-2 Measurement and Uncertainty; Significant Figures(P3-5) Physics is based on measurement of physical quantities(物理量,P3 Significant Figures(有效数字): The number of relia bly known digits in a number is called the number of significant figures P4Chapter 1 Introduction 1-2 Measurement and Uncertainty; Significant Figures(P3-5) Physics is based on measurement of physical quantities (物理量). P3 Significant Figures(有效数字): The number of reliably known digits in a number is called the number of significant figures. P4