Significant Figures Rules: The number of significant figures can be determined by adding up each significant digit within the value using the following rules: 1. All non-zero numbers are significant. a. 531 = 3 sig figs 2. Zeros between non-zero numbers are significant. a. Ex: 105 = 3 sig figs 3. Zeros as placeholders, WITHOUT a decimal, are NOT significant. a. Ex. 100 = 1 sig fig b. Ex. 0.005 = 1 sig fig c. Ex. 0.00503 = 3 sig figs (see rule 2) 4. Zeros as place holders, WITH a decimal, ARE significant. a. Ex. 100. = 3 sig figs 5. A zero after the decimal point as the last value IS considered significant. a. Ex. 0.050 = 2 sig figs (the last two digits of the number are significant) 6. All numbers (including zeros) within the base number for scientific notation are significant. a. Ex. 5.0 * 105 = 2 sig figs 7. When converting numbers into scientific notation, the base should represent the number of significant figures in that number. a. Ex. 1040 = 3 significant figures = 1.04*103 8. Multiplication / Division: The final result should only have as many significant figures as the original value with the least number of significant figures in the calculation. a. Ex. 25 * 355 = 8875 = 8900 The least number of sig figs is 2.