Seeking guidance on effectively using logarithm tables and where to download a four-figure table. Any tips or resources would be appreciated.

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Choose the correct table. To find loga(n), you’ll need a loga table. Most log tables are for base-10 logarithms, called “common logs.”[2]

Example: log10(31.62) requires a base-10 table.

Find the correct cell. Look for the cell value at the following intersections, ignoring all decimal places:[3]

Row labeled with first two digits of n

Column header with third digit of n

Example: log10(31.62) → row 31, column 6 → cell value 0.4997.

Use smaller chart for precise numbers. Some tables have a smaller set of columns on the right side of the chart. Use these to adjust answer if n has four or more significant digits:

Stay in same row

Find small column header with fourth digit of n

Add this to previous value

Example: log10(31.62) → row 31, small column 2 → cell value 2 → 4997 + 2 = 4999.

Prefix a decimal point. The log table only tells you the portion of your answer after the decimal point. This is called the “mantissa.”[4]

Example: Solution so far is ?.4999

Find the integer portion. Also called the “characteristic”. By trial and error, find integer value of p such that

�

�

<

�

a^{p}<n and

�

�

+

1

>

�

a^{{p+1}}>n.

Example:

10

1

=

10

<

31.62

10^{1}=10<31.62 and

10

2

=

100

>

31.62

10^{2}=100>31.62. The “characteristic” is 1. The final answer is 1.4999

Note how easy this is for base-10 logs. Just count the digits left of the decimal and subtract one.