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Precalculus

Work with logarithms

Find log base 10 of a number and undo it with 10 to a power.

Open in Trident

log(x) asks: what power of 10 gives x? Since 10² = 100 and 10³ = 1000, log(250) must be between 2 and 3. It is 2.397940009.

The log key has a partner, 10ˣ, that undoes it. Doing 10ˣ on the answer brings back the 250.

Classic Graphing 84

Start on the main screen: Press 2nd then mode (QUIT) to get back to the home screen. Pressing clear on a menu also backs out of it.

  1. Press log, type 250, close the bracket and press enter.

    log250)enter

  2. Press 2nd then log for 10ˣ, then 2nd and (−) for Ans. Close the bracket and press enter.

    2nd10ˣlog2ndANS(−))enter

You should seelog(250) 2.397940009 10^(Ans) 250

Classic Graphing 84 key reference

Classic Scientific 30

Start on the main screen: Press 2nd then mode (QUIT) to leave any menu or screen and return to the calculation screen.

  1. Press log, type 250, close the bracket and press enter.

    log250)enter

  2. Press 2nd then log for 10ˣ, then 2nd and (−) for Ans, and press enter.

    2nd10ˣlog2ndans(−)enter

You should see10^(Ans) 250

Classic Scientific 30 key reference

Natural Scientific 991

Start on the main screen: Press MENU, then 1 (Calculate) to return to the main calculation screen. AC clears the line you are on.

  1. Press log, type 250 and press =.

    log250=

  2. Press SHIFT then log for 10ˣ, then Ans, and press =.

    SHIFT10logAns=

You should see10^(Ans) 250

Natural Scientific 991 key reference

Natural Color Graphing

Start on the main screen: Press MENU then 1 to open Run-Matrix, the main calculation screen. Press EXIT to back out of a bar or screen, and SHIFT then EXIT (QUIT) to return to the app start.

  1. Press log, type 250 and press EXE.

    log250EXE

  2. Press SHIFT then log for 10ˣ, then SHIFT and (−) for Ans, and press EXE.

    SHIFT10ˣlogSHIFTAns(−)EXE

You should see2.397940009 10^(Ans) 250

Natural Color Graphing key reference

Classic CAS

Start on the main screen: Press home to open the Home menu (Calculator, Graphs, Settings, and more). Choose Calculator, or press esc to go back to the calculation page.

  1. Type log(250) and press ctrl enter for a decimal.

    log250)ctrl≈enter

  2. Press ctrl then log for 10ˣ, then ctrl and (−) for ans, and ctrl enter.

    ctrl10ˣlogctrlans(−)ctrl≈enter

You should see2.39794 10^(ans) 250.

Classic CAS key reference

RPN Scientific 15

Start on the main screen: There is no menu to leave. Press the back arrow to clear a number you are typing, or CLx (g then back arrow) to clear the X register.

  1. Key in 250. Press g then the 10ˣ key to use LOG.

    250gLOG10ˣ

  2. Press the 10ˣ key (with no prefix) to undo it.

    10ˣ

You should see250.0000

RPN Scientific 15 key reference

RPN Advanced 42

Start on the main screen: Press EXIT (once or twice) to close any menu and return to the plain stack view of Y and X.

  1. Key in 250 and press LOG.

    250LOG

  2. Press shift then LOG for 10ˣ.

    ⇧10ˣLOG

You should seex: 250.0000

RPN Advanced 42 key reference

RPN Power 48

Start on the main screen: Press ON to cancel what you are typing, then use the stack view. Open the MODE or VAR menu any time; the stack is always shown above the menu row.

  1. Key in 250. Press the right shift and SIN to get LOG.

    250▶LOGSIN

You should see2.39794000867

Right shift and COS gives 10ˣ.

RPN Power 48 key reference

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