Question

I am doing a average atomic mass question. I have the answer to it, but it says to round it to 3 decimal places. The answer is 39.89982753. I don't know whether to round it to just the 39.899 or to actually round it to it being 39.900. if anyone could help that would be great!!!!

Answer 1

You have to round to 39.900. Leaving it as 39.899 would be an inaccurate representation of the molecule’s approximate value, especially for average atomic mass.

Answer 2

Round to 39.900.

Step-by-step explanation:

You want to round to three decimal places.

39.899 827 53

That means you must drop all the underlined digits.

The rule for rounding is: If the first figure dropped (8) is greater than 5, increase the last figure kept (9) by 1.

Then, rounding 39.899 827 53 to three decimal places gives 39.900.