Using Significant Figures in WebAssign

Significant figures are one way of expressing uncertainty in measurement. The rules WebAssign uses to determine the number of significant figures in a number are shown in the examples below:

1234               =             4 significant figures                     5.0e2 =           2 significant figures

500                   =             1 significant figure             140E-001 =      2 significant figures

500.                 =             3 significant figures         8.20000e3 =       6 significant figures

13000            =             2 significant figures       101.001    = 6 significant figures

2.000              =             4 significant figures     41003            = 5 significant figures

As you can see, most numbers are fairly straightforward.

To express a number like 1000 to 2 or 3 significant figures, you must use scientific notation.

When you multiply or divide numbers, the result of your calculation has the same number of significant digits as the operand with the fewest number of significant figures. For example:

1530 4.0 = 6100

1530 (3 significant figures) 4.0 (2 significant figures) = 6100 (2 significant figures)

When you add or subtract numbers, keep the fewest number of decimal places that are in all of the numbers. For example:

2.46 + 6.1743 = 8.63

2.46 (to the hundredths place) + 6.1743 (to the ten-thousandths place) = 8.63 (to the hundredths place)

4580 - 411 = 4170

4580 (to the tens place) - 411 (to the ones place) = 4170 (to the tens place)

When you take the logarithm of a number, the number of decimal places in the result must be the same as the number of significant figures in the number you started with (Why is this?). For example:

log10(27) = 1.43

log10(27 two significant figures) = 1.43 (two decimal places)

ln(0.026) = -3.65