Calc Guide

more manageable parts, described below, also helps to minimise errors
and aid troubleshooting.
Lack of documentation
Lack of documentation is a very common failing. Many users prepare a
simple worksheet which then develops into something much more
complicated over time. Without documentation, the original purpose
and methodology is often unclear and difficult to decipher. In this case
it is usually easier to start again from the beginning, wasting the work
done previously. If you insert comments in cells, and use labels and
headings, a spreadsheet can be later modified by you or others and
much time and effort will be saved.
Error-checking formulas
Adding up columns of data or selections of cells from a worksheet often
results in errors due to omitting cells, wrongly specifying a range, or
double-counting cells. It is useful to institute checks in your
spreadsheets. For example, set up a spreadsheet to calculate columns
of figures, and use SUM to calculate the individual column totals. You
can check the result by including (in a non-printing column) a set of
row totals and adding these together. The two figures—row total and
column total—must agree. If they do not, you have an error
somewhere.
Figure 124: Error checking of formulas
Chapter 7 Using Formulas and Functions 179