Question about HP 20s Calculator

Hello,

Enter the (positive) number , press [Left Shift: blue][LOG] to calculate log in base 10

12 [Left Shift][LOG] gives 1.079181246.

In general Functions in blue are accessed with left shift. functions in Yellow/Orange are accessed with RIGHT SHIFT.

As to the manual, there is not any around in the Web,except the Spanish version at hp Spain. This is one instance where it pays to speak in (foreign) tongues.

If you want the link, post to this thread and I will be happy to supply it.

Hope it gets you back in gear.

Posted on Oct 04, 2009

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Posted on Jan 02, 2017

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

Press the log key, enter a poistive number and press the = key.

To calculate the inverse of the decimal log use SHIFT LOG to access the function 10^x (the inverse of the log function.)

To calculate the inverse of the decimal log use SHIFT LOG to access the function 10^x (the inverse of the log function.)

Dec 15, 2010 | Sharp ELW535 Calculator

Please use the following link to download the manual for your calculator.

http://www.devicemanuals.com/guide/Calculator/HP/HP-20s-Scientific-Calculator-Owner's-Manual-==TVRFME5UWTE=.html

http://www.devicemanuals.com/guide/Calculator/HP/HP-20s-Scientific-Calculator-Owner's-Manual-==TVRFME5UWTE=.html

Aug 28, 2010 | HP 20s 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

Use the log function (common logarithm). See screen capture for markings
on key.

To evaluate the negative of a logarithm

Enter the number (argument) of the logarithm

Press the = key to have it calculated.

While result is still displayed, press the sign change key or (+/-).

Beware that -log(number) is not necessarily a negative value.

Another way to calculate -log is to use the relation

log(1/a)=-log(a) .

Your example

3 [EXP] [(] [+/-] 2 [) ] [LOG][=] [+/-]

[EXP] is the key to enter exponent of a power of 10 :It is a shortcut, so no 10 is entered. Respect the key sequence above.

[ (] left parenthesis to prevent ambiguity due to the negaticve exponent. Just a security.

[)] is the enclosing right parenthesis

[+/-] is the Sign Change key

To evaluate the negative of a logarithm

Enter the number (argument) of the logarithm

Press the = key to have it calculated.

While result is still displayed, press the sign change key or (+/-).

Beware that -log(number) is not necessarily a negative value.

Another way to calculate -log is to use the relation

log(1/a)=-log(a) .

Your example

3 [EXP] [(] [+/-] 2 [) ] [LOG][=] [+/-]

[EXP] is the key to enter exponent of a power of 10 :It is a shortcut, so no 10 is entered. Respect the key sequence above.

[ (] left parenthesis to prevent ambiguity due to the negaticve exponent. Just a security.

[)] is the enclosing right parenthesis

[+/-] is the Sign Change key

May 06, 2010 | Casio FX-260 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

Hello,

Let y=10^(x) 10 to the power of x

Take the log of both tems of the equality. You get

log(y)=log[10^(x)] where I used square brackets for clarity. But from the general properties of logarithms

log(b^(a)) = a*log(b)

Applied to our expression above

log(10^x)=x*log10

But since we are using log as log in base 10, log_10(10)=1

so

log(y)=x

We thus have two equivalent relations

**y=10^x <----> x=log(y) **The double arrow stands for equivalence.

If**y is the log of x**, then **x is the antilog of y**

Your question: With log_10 standing for logarith in base 10

pH=-log_10(c) c= concentration

Then log_10(c)=-pH the equivalence above translates as

log_10(c)=-pH is equivalent to c=10^(-pH)

The concentartion corresponding to a pH of 7.41 is

c=10^(-7.41)=3.89x10^(-8)

You enter it as follows

10[^]7.41[(-)][ENTER/=]

Hope it helps

Let y=10^(x) 10 to the power of x

Take the log of both tems of the equality. You get

log(y)=log[10^(x)] where I used square brackets for clarity. But from the general properties of logarithms

log(b^(a)) = a*log(b)

Applied to our expression above

log(10^x)=x*log10

But since we are using log as log in base 10, log_10(10)=1

so

log(y)=x

We thus have two equivalent relations

If

Your question: With log_10 standing for logarith in base 10

pH=-log_10(c) c= concentration

Then log_10(c)=-pH the equivalence above translates as

log_10(c)=-pH is equivalent to c=10^(-pH)

The concentartion corresponding to a pH of 7.41 is

c=10^(-7.41)=3.89x10^(-8)

You enter it as follows

10[^]7.41[(-)][ENTER/=]

Hope it helps

Aug 09, 2009 | Sharp EL-531VB Calculator

I have a Saab 900 -97 with a similar problem. I just solved it yesterday on my car. Hold the Band button in for like 10-15 sec when you see "Code In", It clears the error log in the radio. If it doen´t work, enter a wrong code so the code hangs on the display and then press the band button to clear the error log. It worked on my car, good luck!

/Tomas

/Tomas

May 19, 2009 | 1994 Saab 900

Hello,

12 [LN] gives 2.484906650 natural logarithm (ln) of 12

12 [LEFT SHIFT: blue] [LOG] gives 1.079181246 : common log of 12

Hope it helps

12 [LN] gives 2.484906650 natural logarithm (ln) of 12

12 [LEFT SHIFT: blue] [LOG] gives 1.079181246 : common log of 12

Hope it helps

Mar 29, 2009 | HP 20s Calculator

Hello,

You are victim of a confusion between terms. Base-n calculations are calculations using various numeration systems (bases) : binary (2), octal(8) hexadecimal (16) and decimal (10). What you want is how to calculate powers, logarithms, exponentials and these have also the notion of base; Log in base 10 is the common log, whereas natural logarithms, are logarithms in base e.

Back to your exemple: 5 times 5 and raise the whole to power 3?

In that case [(] 5 [x] 5 [)] [^] 3 or [X to the 3] if you have such key or

25 [^] 3, because 5x5 = 25

5 times (5 raised to power 3)

5[x] [( ] 5 [^] 3 [)] or 5 [^] 4 because of the rules about products of powers with the same base.

Hope it helps.

You are victim of a confusion between terms. Base-n calculations are calculations using various numeration systems (bases) : binary (2), octal(8) hexadecimal (16) and decimal (10). What you want is how to calculate powers, logarithms, exponentials and these have also the notion of base; Log in base 10 is the common log, whereas natural logarithms, are logarithms in base e.

Back to your exemple: 5 times 5 and raise the whole to power 3?

In that case [(] 5 [x] 5 [)] [^] 3 or [X to the 3] if you have such key or

25 [^] 3, because 5x5 = 25

5 times (5 raised to power 3)

5[x] [( ] 5 [^] 3 [)] or 5 [^] 4 because of the rules about products of powers with the same base.

Hope it helps.

Feb 17, 2009 | Casio FX-115MS Plus Calculator

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