A note of common logarithm with proportional parts

The logarithmic function is very specific function used widely in
various fields. Generally, we do not know the true value of the
logarithm. So we use an approximation with some digit. Most of
mathematical textbooks provide a table of common logarithm with
proportional parts or not. So we can find an approximate value of the
real number without a calculator. The value of proportional parts in
several tables of common logarithm was found different. According to
the analysis of various types, we propose how to correct use of the
proportional parts in the table of common logarithm.