Section outline

  • 　It refers to the number of digits in a number that has a rational basis as a measured value or analytical value, taking into account measurement accuracy, etc.

    　If you write a concentration value in the answer column of an analytical chemistry test using an absurd (no rational basis) number of digits, such as 12.34567636455, you will be rejected immediately. Even if it is written in the experiment report, it is a considerable negative point.

     

    First, familiarize yourself with significant figures.


    • It's easy to get used to and remember, so I'll show you an example.


      example


      ①　If you write a number as "1.0", the number of significant digits in this number is 2 digits.

      　　　→　This means that there is an error of 1.0 ±0.05.

            (There is an error in the third digit, so the valid number is 2 digits.)

      (The value included in the range of 0.95 ≦ x <1.05)

      ②　If you write a number as "25", the number of significant digits in this number is 2 digits.

      　　　→25 This means that there is an error of ±0.5.

      　　　　(This is a number in the range of 24.5≦x<25.5)

       

      ③　If you write a number as "0.020", the number of significant digits in this number is 2 digits.

      　　　→　This means that there is an error of 0.020 ±0.0005.

      　　　　(This is a number in the range of 0.0195≦x<0.0205)

      ④　If you write a number as "25×102", the number of significant digits in this number is 2 digits.“

      　　　→　This means that there is an error of 25×102 ±0.5×102.

      　　　　（24.5×102≦x＜25.5×102の範囲の数値のことである）

       

      ⑤　If you write a number as "2500", the number of significant digits in this number is 4 digits.

      　　　→　2500 means that it has an error of ±0.5.

      　　　　(This is a number in the range of 2499.5≦x<2500.5)



      Have you gotten used to it yet?