Sig Figs, Measurements, & Scientific Notation

Sig Figs:

  • Basic rules:

    • Sig figs are_:

    • # between two non zero number (ex. 103)

    • zeros to the right of a non-zero number are NOT significant UNLESS there is a decimal at the end (100→ only 1 sig fig) (100. → 3 sig figs)

    • starting zeros to a decimal are NOT significant (0.00043 → only 2 sig figs)

    • trailing zeros to a decimal ARE significant (0.4300 → 4 sig figs)

    • 10.0 has 3 sig figs as well!

    • scientific notation: all numbers before multiplication sign are sig figs (1.03×105) → 3 sig figs


  • Adding & Dividing:

    • only the sig figs after the decimal are counted and lowest is the answer total (ex. 43.25+22.2 = 65.45 → 65.5)

    • 2 decimal sig figs + 1 decimal sig fig equals = 1 decimal sig fig

  • Multiplying & Dividing:

    • all sig figs are counted, and the least number is the total number of the answer of sig figs (ex: 43.25 × 22.2 = 960.15 → 960)

    • 4 sig figs x 3 sig figs = 3 sig figs

Measurements

  • Being specific: read to smallest unit on measuring device

  • always add 2 decimal places (usually a 0)

  • last number is ESTIMATED

  • practice:

  • 20.40ml

  • 1) 2.30 cm

  • 2) 2.35 cm

Scientific Notation

  • calculator: first number + (2nd+x1) + exponent

  • IF EXPONENT IS NEGATIVE THEN USE (-) before writing notation