Si units and sig figs
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SI units and sig figs. SI (système internationale). Precision: the reproducibility, under the same conditions, of a measurement . These points are precise with one another but not accurate. Accuracy: the closeness of a measurement to the true value of what is being measured.

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Using sig figs the rules
Using sig figs: The Rules! of what is being measured.

  • Digits from 1-9 are always significant.

  • Zeros between two other significant digits are always significant

  • One or more additional zeros to the right of both the decimal place and another significant digit are significant.

  • Zeros used solely for spacing the decimal point (placeholders) are not significant.


Multiplying and dividing
Multiplying and Dividing of what is being measured.

  • RULE: your answer may only show as many sig figs as the multiplied or divided measurement showing the least number of significant digits.

  • Example: 22.37 cm x 3.10 cm = 69.3 only 3 sig figs allowed.


Adding and subtracting
Adding and Subtracting: of what is being measured.

  • RULE: your answer can only show as many decimal places as the measurement having the fewest number of decimal places.

  • Example:

    3.76 g + 14.83 g + 2.1 g = 20.7 g


Scientific notation
Scientific Notation of what is being measured.

  • Scientists have developed a shorter method to express very large numbers.

  • Scientific Notation is based on powers of the base number 10.


  • 123,000,000,000 in s.n. is of what is being measured.1.23 x 1011

  • The first number 1.23 is called the coefficient. It must be between 1 - 9.99

  • The second number is called the base . The base number 10 is always written in exponent form. In the number 1.23 x 1011 the number 11 is referred to as the exponent or power of ten.


To write a large number in scientific notation ex 36 000
To write a large number in scientific notation: of what is being measured.ex: 36 000

  • First put the decimal after the first digit and drop the zeroes. Ex: 3.6

  • Next, count the number of places from the decimal to the end of the number. Ex: 4

  • Finally, put it together. Ex: 3.6 x 104


To write a small number in s n ex 0 00064
To write a small number in s.n. of what is being measured.ex: 0.00064

  • First move the decimal after the first real number and drop the zeroes. Ex: 6.4

  • Next, count the number of places moved from the original decimal spot to the new decimal spot. Ex: 4

  • Numbers less than 1 will have a negative exponent. Ex: -4

  • Finally, put it together. Ex: 6.4 x 10-4


Significant digits
Significant Digits of what is being measured.

  • When using a measuring device, there is a last number estimation.

  • The accuracy of the sig figs depends upon the measuring device.

  • Ex: a ruler.


Read the ruler
Read the ruler of what is being measured.


Si prefixes
SI Prefixes of what is being measured.


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