Calculator gives wrong answers for log

5,874

If you want the base-15 log of 50625, you need to calculate $(\log 50625) ÷ (\log15)$. If you do this you'll get the answer 4.

Similarly if you calculate $(\log 1000) ÷ (\log 10)$ you will get 3.

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DowinskiField
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DowinskiField

Updated on March 10, 2020

Comments

  • DowinskiField
    DowinskiField over 3 years

    $10^3 = 1000$

    My calculator with $10\log(1000)$ gives $30$

    $15^4 = 50625$.

    My calculator with $15\log(50625)$ gives $70.57$.

    What am I doing wrong? Or would there be something wrong with my properties? I am using a Casio fx-82MS.

    Thanks in advance,

    Jarno

    • Zubzub
      Zubzub over 6 years
      Well $\log(50625) \approx 4.704$ so your calculator is right. But your reasoning is not !
    • The Count
      The Count over 6 years
      in the second line, you are multipying 10 by the number you want. log just means log with a base of ten. the 10 and 15 headers are unnecessary.
    • Cato
      Cato over 6 years
      $10Log(1000) = Log(1000^{10}) = Log((10^3)^{10}) = Log(10 ^ {30}) = 30$
    • DowinskiField
      DowinskiField over 6 years
      Hmm.. so how will I go back to 15^4 with the log function?