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Display Numbers to a Specified Precision

You can use the sigform() and decform() functions to display numeric values to a specified number of significant digits or decimal places.

How-ToInstructor HelpWebAssign
sigform()

Displays a value rounded to the specified number of significant digits. If needed, e notation is used.

The sigform() function is usually used when significant figures are important, such as scientific measurements.

decform()

Displays a value rounded to the specified number of decimal places.

The decform() function is typically used to display like values in the question with a consistent and reasonable precision, for example, to two or three decimal places.

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  2. In an <EQN> or <eqn> tag, use either the sigform() or decform() function to display a numeric value.

    Specify the number of significant digits

    Use the following syntax:

    sigform(n, digits)

    where n is the number you want to format, and digits is a positive integer specifying the number of significant digits to use.

    Specify the number of decimal places

    Use the following syntax:

    decform(n, digits)

    where n is the number you want to format, and places is a non-negative integer specifying the number of decimal places to use.

    For example:

    # sigform examples

$shortpi = sigform($pi,3);   #  3.14
$a = sigform(100,1)          #  100
$b = sigform(100,2)          #  1.0e+02

#decform examples

$shortpi = decform($pi,3);   #  3.142
$a = decform(100,1)          #  100.0
$b = decform(100,2)          #  100.00

Example Question Using sigform() The following table summarizes an actual question. QID 1940827 Name Mode Numerical Question <eqn> # Pick two different significant figures for the measurements ($m_sigfigs,$v_sigfigs) = pick(2,2..5); # Randomize measurements & round to the specified significant figures $mass = sigform(randnum(300000,1200000,1)/100000,$m_sigfigs); $volume = sigform(randnum(106000,110000,1)/100000,$v_sigfigs); # Calculate answer key and determine correct significant figures $density = $mass/$volume; $d_sigfigs = min($m_sigfigs,$v_sigfigs); '' </eqn> In the lab, you measure the displacement of a metal sphere as <eqn $volume> liters.<BR/> You also determine its mass to be <eqn $mass> kg.<BR/> Calculate its density. <_> kg/l Answer <EQN $SIGFIGS=$d_sigfigs; $density> Display to Students Example Question Using decform() The following table summarizes an actual question. QID 1944303 Name Mode Numerical Question <eqn> # Pick the number of decimal places for the problem ($decimals) = pick(1,2..4); # Randomize addends $a = decform(randnum(100000,999999,1)/10000,$decimals); $b = decform(randnum(100000,999999,1)/10000,$decimals); '' </eqn> <watex>\begin{array}{r} $a \\ + $b \\ \cline{0-0} <_> \end{array}</watex> Answer <EQN $SIMPLIFIED=1; decform($a + $b, $decimals)> {tab} 0 Display to Students