If you're behind a web filter, please make sure that the domains *.kastatic.org and *.kasandbox.org are unblocked.

Logarithms

Calculator for natural logarithms

Calculator for Natural Logarithms
Back

Calculator for natural logarithms

Discussion and questions for this video
ln = logarithmus naturali Latin not French.
Comment
In french, ln = logarithme népérien, which translates to "Néper's logarithm'. Néper is a frenchization of Napier, as in john Napier (http://en.wikipedia.org/wiki/John_Napier), who invented logarithms.
Comment
Why are ln and e so important?
Comment
Invest $1.00 at 100% interest for 1 year. Compound: Quarterly:$2.44
Monthly: $2.61 100 times:$2.70
1,000 times: $2.72 10,000 times:$2.72
100,000 times: $2.72 1,000,000 times:$2.72

You eventually compound that one dollar so much annually that this is called "compounding continuously".
The value is approaching a limit called "e".

That's why e is so important. To compound continuously.

Comment
Are there any videos are playlists specifically covering "e"?
Comment
Thanks Marty! I looked and I found http://www.khanacademy.org/math/precalculus/v/introduction-to-compound-interest-and-e in case anyone else is looking.
Comment
okay so, on the topic of natural logs, could there be some videos where the application of natural logs is necessary?
Comment
I think logs and natural logs are also used for continuously compounded interest rates banks use for your bank accounts. I don't want to be a parrot, but from an in class lecture my professor gave a little backstory about Euler, banks using it as some scheme to lure customers away from competing banks, and to help give some explanation behind certain measurements naturally occuring in plants.
Comment
why is ln (-1) undefined??
1 Comment
Good Question!
It's the same as saying 'e' to what power equals negative one
e^x = -1
There is no real number for x that makes that equation true
Comment
Actually it stands for "logarithme neperien" in frensh
Comment
At 0:45,what is mantisa
1 Vote
Comment
The mantissa of a logarithm is the decimal portion of the answer. We usually speak of the mantissa when dealing with the common log rather than the natural log.

For example, log₁₀ (152) = 2.18184 (rounded off)
The mantissa is 0.18184...
The characteristic (which is the integer portion of the answer) is 2.

This is mostly just a curiosity nowadays, since calculators and computers have made needing to separate the characteristic and the mantissa obsolete.
Comment
how do i use the calculator for e to the 0.24?
1 Vote
Comment
press the e button
press the ^ button
type in .24
press =
Comment
how do you find "ln" on a TI-84 plus calculator? if you can't, then how would you start to solve the problem 2e^2ln-4 - ln e^8 ?
1 Vote
Comment
it's the button directly on the left of 4
Comment
If you get a question that says round to the nearest hundredth (for example) and you got a number like 1.1, would you have to put the extra zero at the end, or could you just keep it as 1.1 since the final zero is not needed?
1 Vote
Comment
It is an issue of significant figures. If the numbers you are given have that accuracy, then there is a point to adding the zeros, additionally for computer-inputed answers. For paper grading without significant figure requirements it should not matter.
1 Vote
Comment
I am having trouble finding the correct answer on a calculator for P(t)=10000e^ln10/17 over 8 times 10? I'm not sure how to enter it. I have been playing around with examples and I am not coming up with the correct answer. Please help.
1 Vote
Comment
I'm not sure if you mean (e^ln10)/17 or e^ln(10/17), but either way it works out the same. The natural log is defined as what power you need to raise e to to get a number, so e^ln of something is just that something. So we have 10,000*10/(17*8*10) = 10,000/(17*8) = 1,250/17. On a calculator, you would press the buttons like this:
10000
times
(
(
10
÷
17 (10/17)
)
ln(x) (natural log of 10/17)
)
= (10000 times the natural log of 10/17)
÷
80
=
1 Vote
Comment
Im having trouble figuring out how to use my calculator (TI-30XA) to answer x= In(3/5)-1 / 2

The answer is .755 but I dont know how to get there.
1 Vote
Comment
how do I use calculator to logarithm function division problems
1 Vote
Comment
Could we please have some videos explaining more about what e is, where it came from, and how it's useful? Thanks!!
1 Vote
Comment
Try watching sal's vids on "compound interest and e"
1 Vote
Comment
so is there a section for natural logs like this: 1+LN(x)2=6 (one plus natural log x squared equals six)
1 Vote
Comment
To solve that I would start by subtracting 1 from both sides.
1 Vote
Comment
log(2x+1)= 1+log(x-2)
1 Vote
Comment
how to check answers using a log table?
1 Vote
Comment
how to change the base of log from "e " to base 10
1 Vote
Comment
C=2pier solve for r
1 Vote
Comment
Why is ln(0) undefined?
1 Vote
Comment
For the same reason that log(0) is undefined for any other base. For b ≠ 0, there is no x such that b^x = 0.
1 Vote
Comment
Find the interest of \$23,400 at 14.5% for 24 months
1 Vote
1 Comment
what is the best way to deal with natural logarithm word problems?
any thing in particular i might want to look for?
even non-natural logarithms, what's a real life senario where they might apear?
1 Vote
Comment
How do you deal with logarithms when placed in word problem form, or real life?
1 Vote
Comment
I'm just wondering, but how does "e" show up in nature and finances?
1 Vote
Comment
There is a connection to compound interest frequency, thats how the constant was discovered.
http://en.wikipedia.org/wiki/E_(mathematical_constant)#Compound_interest

One example where e occurs naturally is the capstan equation.
http://en.wikipedia.org/wiki/Capstan_equation
1 Vote
Comment
2log6(x+9)=log6(36+2)
Comment
Discuss the site

Flag inappropriate posts

Here are posts to avoid making. If you do encounter them, flag them for attention from our Guardians.

abuse
• disrespectful or offensive
• low quality
• not about the video topic