Why must a calculated answear generally be rounded? and

how many siginificant figures must you round an answear to when performing multiplication or division?

http://chemed.chem.purdue.edu/genchem/topicreview/bp/ch1/sigfigs.html

A calculated answer typically needs to be rounded because the measurements or values used in calculations often have limitations in terms of precision. When performing calculations, it is important to consider the number of significant figures (digits that contribute to the precision) in the measurements or values being used.

When performing multiplication or division, the rule for determining the number of significant figures in the answer is as follows:

1. Multiplication: The answer should be rounded to the same number of significant figures as the measurement with the fewest significant figures. For example, if one measurement has two significant figures and another has three significant figures, the answer should be rounded to two significant figures.

2. Division: The answer should be rounded to the same number of significant figures as the measurement with the fewest significant figures. For example, if one measurement has two significant figures and another has three significant figures, the answer should be rounded to two significant figures.

It is important to note that the concept of significant figures is based on the precision of the measurements used in calculations and is not related to the number of decimal places. The significant figures in a number indicate the degree of uncertainty or precision associated with that value.