How to calculate log base 10 with log tables?
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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."
Example: log10(31.62) requires a base-10 table.
Example: log10(31.62) requires a base-10 table.
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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.
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.
4
Prefix a decimal point. The log table only tells you the portion of your answer after the decimal point. This is called the "mantissa."
Example: Solution so far is ?.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."
Example: Solution so far is ?.4999
Similar questions
Find the correct cell. Look for the cell value at the following intersections, ignoring all decimal places:
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.