Question about Casio FX-7400G Plus Calculator

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For logarithms one uses one of two keys

**[LOG] for logarithms in base 10**. It is in the same column as the F1 key, on 4th row**[LN] for natural logarithms.**It is in the same column as the F2 key, fourth row, to the right of the [LOG] key.

Posted on Dec 17, 2009

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Posted on Jan 02, 2017

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The Casio FX-300MS does not provide base 2 logarithms as a single key operation. However, you can use the natural logarithm (ln, base e = 2.7182818...) and the formula

log2 ( x ) = ln( x ) / ln( 2 )

To calculate the base 2 logarithm of 16, key in

[ln] 16 [/] [ln] 2 [=]

and get displayed the correct answer 4.

The same simple formula also works for any other base, and actually for any other logarithms provided by your calculator. The FX-300MS also provides a logarithm to base 10 (lg). You could also

type

[lg] 16 [/] [lg] 2 [=] to get the solution to the problem above, or

[lg] 25 [/] [lg] 5 [=] to get the base 5 logarithm of 25.

log2 ( x ) = ln( x ) / ln( 2 )

To calculate the base 2 logarithm of 16, key in

[ln] 16 [/] [ln] 2 [=]

and get displayed the correct answer 4.

The same simple formula also works for any other base, and actually for any other logarithms provided by your calculator. The FX-300MS also provides a logarithm to base 10 (lg). You could also

type

[lg] 16 [/] [lg] 2 [=] to get the solution to the problem above, or

[lg] 25 [/] [lg] 5 [=] to get the base 5 logarithm of 25.

Mar 20, 2014 | Casio FX-300MS Calculator

To calculate the natural antilogarithm (inverse logarithm ) of a number, press SHIFT [e^x] then enter the number and press =

The e^x function is the shifted function of the ln key.

For example, to calculate the inverse logarithm of 3, press SHIFT ln 3 =

The e^x function is the shifted function of the ln key.

For example, to calculate the inverse logarithm of 3, press SHIFT ln 3 =

Nov 06, 2013 | Casio FX-300MS Calculator

To calculate the natural antilogarithm (inverse logarithm ) of a number, press SHIFT [e^x] then enter the number and press =

The e^x function is the shifted function of the ln key.

For example, to calculate the inverse logarithm of 3, press SHIFT ln 3 =

The e^x function is the shifted function of the ln key.

For example, to calculate the inverse logarithm of 3, press SHIFT ln 3 =

Nov 06, 2013 | Casio FX-300MS Calculator

Depending on the actual log function you are talking about, the inverse function (what you call the anti log) can be one of several things.

The inverse of the natural log (LN) is the exponential function** e^x**.

**If y= ln(x) then x=e^y **

On a calculator functions that are inverse of one another share the same physical key.**If one function is marked on a key, the inverse function is usually the SHIFTED (or 2nd) key **

The inverse of the common (decimal logarithm) is the power function with 10 as base.

Example:** if y= log(x) then x=10^y**

For an arbitrary base (must be positive)** if y= log_b(x) then x=b^y**.

Note: I do not think that the FX-300ms can perform log calculations in bases other than e (natural log) or 10 (common decimal log).

The inverse of the natural log (LN) is the exponential function

On a calculator functions that are inverse of one another share the same physical key.

The inverse of the common (decimal logarithm) is the power function with 10 as base.

Example:

For an arbitrary base (must be positive)

Note: I do not think that the FX-300ms can perform log calculations in bases other than e (natural log) or 10 (common decimal log).

Aug 13, 2011 | Casio FX-300MS Calculator

Use the "log" key in the third row of the keyboard. This is for the common (base 10) logarithm. The "ln" key next to is for the natural (base-e) logarithm.

Mar 29, 2011 | Casio FX-300MS Calculator

Your calculator is set to degrees. To change to radians, press SHIFT MODe and select Rad.

Jan 30, 2011 | Casio FX-300MS Calculator

You have two keys [LN] and [LOG], the former to calculate the natural logarithms and the latter to calculate the logarithms in base 10.
You press the appropriate function key then type in the value. No need to press the [=] sign.

In case you are wondering: these functions have inverses: the inverse function of [LN] is the exponential, accessed with the key sequence [SHIFT][LN]; the inverse function of the logarithm in base 10 is "raise to to a power", accessed with the key sequence [SHIFT][LOG].

I am enclosing a screen capture from the user's manual. It shows you several examples.

In case you are wondering: these functions have inverses: the inverse function of [LN] is the exponential, accessed with the key sequence [SHIFT][LN]; the inverse function of the logarithm in base 10 is "raise to to a power", accessed with the key sequence [SHIFT][LOG].

I am enclosing a screen capture from the user's manual. It shows you several examples.

Aug 24, 2010 | Casio FX-300MS Calculator

The Casio FX-300MS cannot compute directly the logarithm in a base other than 10 or e (natural logs.) But do not despair: there is a way to do the calculations albeit indirectly. One has to use the relation:
log in base a of number b =l**og_a(b)=log(b)/log(a)** where log stands for log in base 10.
You can also use a similar relation valid for natural logs
l**og_a(b)=ln(b)/ln(a).**

Aug 13, 2010 | Casio FX-300MS Calculator

Hello,
There is a key for that, the one labeled [ln] for natural logarithm. For log in base 10 use the key [LOG]
[LN] 10 [ENTER] gives 2.302585093.
As you certainly know, you cannot take the logarithm of a negative number, nor of Zero.

Hope it helps.

Hope it helps.

Nov 01, 2009 | Casio FX-300MS Calculator

Hello,

Sorry I clicked the post a clarification request too fast.

You cannot compute it directly. You have to use the formula

log_18(number) = ln(number)/ln(18).

Here log_18 is log in base 18, ln is the natural logarithm (naeperian or log in base e).

Alternatively, you can use

log_18(number) = log(number)/log(18)

where log is log in base 10.

If you use those types of calculations a lot, it might be a good idea to get a Casio FX-115ES, or a Casio FX-991 ES. They have other nice features like fraction calculations and radicals.

Hope it helps.

Sorry I clicked the post a clarification request too fast.

You cannot compute it directly. You have to use the formula

log_18(number) = ln(number)/ln(18).

Here log_18 is log in base 18, ln is the natural logarithm (naeperian or log in base e).

Alternatively, you can use

log_18(number) = log(number)/log(18)

where log is log in base 10.

If you use those types of calculations a lot, it might be a good idea to get a Casio FX-115ES, or a Casio FX-991 ES. They have other nice features like fraction calculations and radicals.

Hope it helps.

Oct 15, 2009 | Casio FX-300MS Calculator

Jun 10, 2013 | Casio FX-7400G Plus Calculator

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