Numerical Accuracy

In engineering problems of practical significance, the data are seldom known with an accuracy greater than 0.2%. Hence, the answers to such problems should not be written with an accuracy greater than 0.2%. Calculations are often performed by electronic calculators and computers, usually carrying eight or nine digits. So, the possibility exists that numerical result will be reported to an accuracy that has no physical meaning. Throughout this book, we usually follow a common engineering rule to report the final results of calculations:

• Numbers beginning with “1” are recorded to four significant digits.

• All other numbers (that begin with “2” through “9”) are recorded to three significant digits.