Question

Add these measurements, using significant digit rules: 1.0090 cm + 0.02 cm = cm

Answer 1

Answer:  " 1.03 " .

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Explanation:

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When we add "measured" or "obtained values" ; the rules for "signficant digits" (also known as "significant figures" ; or "sig figs")  are different from the rules we use when we multiply "measured or obtained values".

We are given 2 (two) "measured or obtained values" ; and we are asked to add these values together using the "significant digit rules.

In this case, we add up the "sum total value" of all the values—Not taking into account the number of significant figures.  Then, we take that "sum value" ; and we round that value to the number of "decimal places" that corresponds to the the number of decimals places in the "measured/obtained valued" that occurs in the value using to calculate the sum —the one that also happens to have the least number of significant digits among all the values used to calculate the "sum total".

As such:

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              1.0090 cm

+            0.02      cm          

      ________________    

           1.0290  cm.                                    

                                   

 →  Now, there were two (2) values used to calculate the "sum total" ;

1)  1.0090 cm ; which has 5 (five) significant digits.

2)  0.02 cm ;  which as 1 (one)  significant digits.

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 So, " 1" is less than "5" ;  so:  " 0.02" is the value within the calculations used to find the sum total — that has the "least" number of significant digits.    

  →  " 0.02 " ;  happens to have 2 (two) decimal spaces.

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So, we take the "sum total" :

      →   "  1.0290 cm " ;

      →  And round this number to:  " 2 (two) decimal places:

            → 1.029... ;  

      →  If the number after the second decimal place is from "1 to 4" ; we round down.  If the number after the second decimal place is

from "5 and 9" ; to round up.  Since the third decimal place is:  "9" ;

  [Note:  " 1.029.." ;  is between "5 to 9" } ; we round up:

→  The answer is:  " 1.03 " .

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Hope this is helpful to you!

     Wishing you the best!

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