# Important Things to Remember about Logs

(or else...)

Logs make it easier **to compare measurements that vary by many orders of magnitude**.

**Positive logs** mean big numbers – bigger than one.

To find the approximate log, simply **count the number of digits AFTER the first digit**.

**Negative logs** mean small numbers – between zero and one.

To find the approximate log, **count the decimal point plus number of zero's** UNTIL the first non-zero digit.

Logs are the same as the exponent you would need to put on a "10" in order to get your original
measurement: in other words, **The Log is the Power**.

Going UP BY ONE on a log scale is always the same as multiplying by 10. Going DOWN BY ONE on a log scale is always the same as dividing by 10.

You can **recover the original measurement** by raising 10 to the log
( or "10^___ =" on Google).

The **pH scale **is based on the NEGATIVE log of concentration of H^{+} ions.

The** Richter scale** is based on the log of energy released.

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