--- loncom/html/adm/help/tex/Significant_Figures.tex	2002/07/05 16:12:31	1.1
+++ loncom/html/adm/help/tex/Significant_Figures.tex	2013/07/08 18:13:08	1.5
@@ -1,10 +1,26 @@
+\label{Significant_Figures}
 A \textbf{significant figures} specification tells the system how many significant
-figures there are in the problem, as either a single number or a range of
+figures there are in the problem, as either a single number, e.g. 3, or a range of
 acceptable values, expressed as \textbf{min,max}. The system will check to
 make sure that the student's answer contains this many significant digits,
-useful in many scientific calculations. For example, if the problem has three
-significant digits, the significant digit specification is {}``3'', and
-the answer is {}``1.3'', the system will require the students to type {}``1.30'',
+useful in many scientific calculations. For example, if the computer answer is {}``1.3'',
+ane the problem requests three significant digits, specified by (entered without quotes) 
+{}``3'',  the system will require the students to type {}``1.30'',
 even though numerically, {}``1.3'' and {}``1.30'' are the same. A significant
-figure specification of {}``3,4'' means both {}``1.30'' and {}``1.300''
-are acceptable.
\ No newline at end of file
+figure specification of (entered without quotes) {}``3,4'' means both {}``1.30'' and {}``1.300''
+are acceptable. The significant figures field can be omitted if you do 
+not want to constrain the number of significant digits in the student answers.
+
+Note that care must be used when generating and formating computer answers.
+You must assure that the specified answer format provides for enough significant digits.
+To test the formatted answer, LON-CAPA converts the computer answer,
+as generated in the script block, according to the
+format attribute in the numericalresponse tag.
+Then LON-CAPA separately applies that number of significant
+figures to the computer answer, and if that result
+falls outside the range specified in the significant digit parameter, 
+it "grades" the computer answer as SIG\_FAIL (i.e., not correct). This helps assure
+that you have enough significant digits in the formatted answers you display to the students.
+It is a good idea to use the problem testing environment to test plenty of different
+randomizations to make sure that your format and sig digits parameters are compatible.
+