How to Enter Logarithms on Your Graphing Calculator

Filed under Difficulty: Easy, TI-83 Plus, TI-84 Plus, TI-89, TI-92 Plus.

Most graphing and scientific calculators have the ability to calculate logarithms, but you might come across questions which require you to use a different base than your calculator’s built-in functions. Thankfully, there is a simple formula called the “change of base” formula that allows you to calculate any logarithm on your calculator:

logarithm base change1 How to Enter Logarithms on Your Graphing Calculator

Your calculator may have simply a ln( or log( button, but for this formula you only need one of these:

logarithm base change2 How to Enter Logarithms on Your Graphing Calculator

For example, to evaluate the logarithm base 2 of 8, enter ln(8)/ln(2) into your calculator and press ENTER. You should get 3 as your answer. Try it for yourself!

log change of base How to Enter Logarithms on Your Graphing Calculator

One Response to How to Enter Logarithms on Your Graphing Calculator

  1. zoeann anper

    very helpful for a young smart mind like mine. In canada ( where i live) they don’t teach us how to use a dumb american invented calc. much love zoeann

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