Uncertain digits

We may keep digits only as far to the right as the uncertain digit in the least accurate measurement. For example, suppose you measured a block with the millimeter ruler as 4.33 cm, and another block with the centimeter ruler as 2.1cm. What is the length of the two blocks together ... 

Do the two grapefruits have the same mass The answer depends on which set of results you consider. Thus a conclusion based on a series of measurements depends on the certainty of those measurements. For this reason, it is important to indicate the uncertainty in any measurement. This is done by always recording the certain digits and the first uncertain digit (the estimated number). These numbers are called the significant figures of a measurement. 

Significant figures the certain digits and the first uncertain digit of a measurement. (A1.5)... 

Significant figures are digits known with certainty as well as one estimated, or uncertain, digit. 

The significant figures in a number are ali of the certain digits plus the first uncertain digit. 

Certain standard practices and conventions make the taking and reporting of measurements more consistent. One of the conventions that scientists use for reporting measurements is to report all of the certain digits and one estimated (and thus uncertain) digit. 

The uncertain digit represents the degree of doubt in a single measurement. 

Side chain (of amino acid) the hydrocarbon group on an amino acid represented by H, CH3, or a more complex substituent. (22.6) Sigma (cr) bond a covalent bond in which the electron pair is shared in an area centered on a line running between the atoms. (9.1) Significant figures the certain digits and the first uncertain digit of a measurement. (1.4)... 

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