Question 103687
You could probably use Google to find out about the natural log 
and the common log.
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Common log:
log means "exponent"
log25 means "the power of 10 that gives you the number 25"
log25 = 1.39794....
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Natural log:
ln means "exponent"
ln25 means " the power of e that gives you the number 25"
ln25 = 3.218875....
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Cheers,
Stan H.