## Logarithms and calculators

Base 10 logs

log 2 = .301

log 3 = .477

log 5 = .699

log 7 = .845

How to remember these

log 2 = 2 * .15

log 3 = 3 * .16

log 5 = 5 * .14

log 7 = 7 * .12

So it starts at .15, goes up to .16, down to .15 at log 4 and .14 at log 5 and .13 at log 6 and .12 at log 7.

These are approximations. Using a calculator like Google can check how accurate they are.

Just remember .16 for 3. Then count down by .01 in either direction per whole number. This approximately works up to 10. You can straight line interpolate between whole numbers using the same slope. You can then work on improvements to this rule.

http://www.karlscalculus.org/l6_3-2.html

http://oldmathdognewtricks.blogspot.com/2012/05/my-version-of-log-wars.html ## About New Math Done Right

Author of Pre-Algebra New Math Done Right Peano Axioms. A below college level self study book on the Peano Axioms and proofs of the associative and commutative laws of addition. President of Mathematical Finance Company. Provides economic scenario generators to financial institutions.
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### 5 Responses to Logarithms and calculators

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The logical relationship to each other, but also not too hard to remember.

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