21_pdfsam_2 - Quantity 4782 600 6.0 × 102 6.00 × 102...

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Unformatted text preview: Quantity 4782 600 6.0 × 102 6.00 × 102 31.72 30.02 46.0 0.02 0.020 600.00 Signficant Digits 4 1, 2, or 3 2 3 4 4 3 1 2 5 Table 2.1: Significant digits Examples: • (2.43)(17.675) = 42.95025 =⇒ 43.0 • (2.279h)(60 min/h) = 148.74 min =⇒ 148.7 min The conversion factor is exact (a definition). • (4.00 × 102 kg)(2.2046lbm/kg) = 881.84lbm =⇒ 882.lbm The conversion factor is not exact, but it should not dictate the precision of the result if this can be avoided. A conversion factor should be used that has one or two more significant figures than will be reported in the result. • 589.62/1.246 = 473.21027 =⇒ 473.2 Addition and subtraction: The result should show significant digits only as far to the right as is seen in the least precise number in the calculation. Examples: • 1725.463 + 189.2 + 16.73 = 1931.393 =⇒ 1931.4 • 897.0 − 0.0922 = 896.9078 =⇒ 896.9 Combined operations: While it would be good practice to convert the result of each operation to the proper number of signficant digits before applying another operation, it is normal practice to perform the entire calculation and then report a reasonable number of significant figures. Rounding: In rounding a value to the proper number of significant figures, increase the last digit retained by 1 if the first figure dropped is 5 or greater. For example, consider the rounding performed by Matlab in displaying results in short format: >> 2/9, 2.222222222222/4, 2/3, -2/3 34 ...
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This note was uploaded on 03/07/2010 for the course ENG 101 taught by Professor Chang during the Summer '09 term at 東京国際大学.

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