What is the sum of 334.540 g and 198.9916 g to the correct significant figure?

1 Answer
Oscar L.
Jul 20, 2016

#533.532" g"#.

Explanation:

The rule for adding or subtracting numbers with finitely many significant digits is:

1) Find the lowest power of 10 place value with significant digits in both terms

2) Round the sum or difference to that power of 10.

So:

1) The number #335.540# has significant digits down to a place.value of #10^{-3}# (three places past the decimal point); a terminal zero after a decimal point is considered a significant digit. The number #198.9916# has significant digits down to the #10^{-4}# place but the other term does not match that.

2) So round your sum to a multiple of #10^{-3}#, keep three digits to the right of the decimal point.

Thus #334.540+198.9916=533.5316=color(blue)(533.532)#.

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