How do you find the ln of a number? For example, the ln of 18 = 2.89...?

Question

I would like to know what ln is, how to find the ln of a number, and what buttons to use on the calculator.

Answer 1

For any positive number x, ln x refers to the "natural logarithm" of x. If y = ln x, then y is the number for which e^y (e raised to the yth power) is equal to x, where e is known as the base of the natural logarithm. e is approximately equal to 2.7182818.

For example, since ln 18 = 2.89 (approximately, as you said, that means that e^(2.89...) = 18.

It is difficult to compute the ln of most numbers without a calculator, though. However, there are properties of ln that are helpful: ln 1 = 0, ln e = 1, and ln x^b = b* ln x.

Many calculators include a button for ln, or they might include a button for the "common logarithm", which uses base 10 instead of base e. It is denoted by log x, so y=log x meanx 10^y = x.

Answer 2

Lets start with the basics
You know that 4^2=16
We define the exponent 2 to be the logarithm of 16 to the base of 4. This is expressed as follows: log4 (16) = 2
When we are talking about a log to the base of e, we say ln. For example loge(y)=ln(y)
You can calculate it in every calculator with the ln button or in excel ln function

Answer 3

Even a simple calculator like the TI30 will do this for you. Just type in 18 and hit the LN button, you'll see 2.89 in the display.
LN is the natural logartihm and it involves Euler's number. (e^x=2.7182818). If you type in 2.89 e^x you get 18 as your answer again.

Answer 4

Matt is ideal. If x > 0 then ln(-x) = ln(x) + i*pi, so contained in the expression ln(-e) - ln(-a million/e), the imaginary elements will cancel. EDIT: This assumes that we chosen the critical branch of the organic logarithm. If we view the organic logarithm as a multivalued function then ksoileau's answer is ideal. reaction: ln(a million/x) = -ln(x) is valid at the same time as x > 0, yet would fail for different values of x, if we settle on a critical branch of the organic logarithm. case in factor, ln(a million/(-a million)) = ln(-a million) = pi*i. an same difficulty arises with sq. roots of negative numbers. think about considered proper right here "information": a million = sqrt(a million) = sqrt((-a million)*(-a million)) = sqrt(-a million) * sqrt(-a million) = i * i = -a million

Answer 5

Ln is natural logarithm. Use the LnX key or the 1/e^x key.