Significant Digits

1
Significant Digits
2
Rules for determining how many SDs are in a
number

• If it is not zero, it IS significant!
• Ex all digits are significant in
• 45.2 cm
• 91,722 mL
• 1.2 kg
• Zeros in a zero sandwich ARE significant!
• Ex all significant in
• 405 Mm
• 23,009 L
• 100,003 ng

3
Rules for determining how many SDs are in a
number

• If no decimal is showing, zeros to the right ARE
  NOT significant!
• Zeros are not significant in
• 3400 dg
• 300 L
• 12,450 pm
• In small decimal numbers, zeros to the left ARE
  NOT significant!
• Zeros are not significant in
• 0.0023 ng
• 0.231 m
• 0.000056 kL

4
How many SDs in

• 506 L
• 11.09 mg
• 5600 km
• 0.0026 dL
• 45.00 s
• 0.000650 mm

5
Multiplication/Division using SDs

• Least total SDs!
• The number with the smallest amount of
  significant digits determines how many SDs are
  in your answer
• Examples
• 5.670 m X 3.4 m
• 19 m2
• 45.60 m / 3.70 s
• 12.3 m/s

6
Addition and Subtraction Using SDs

• Least significant placeholder
• The number with the least significant placeholder
  determines the least significant placeholder in
  your answer.
• Ex.
• 409.34 cm 23.7 cm
• 385.6 cm
• 3.85 g 24.901 g 200.7 g
• 229.5 g