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Ln

LN Function

The LN function in Excel is used to calculate the natural logarithm of a given number. The natural logarithm is the logarithm to the base e (approximately 2.718), which is a mathematical constant.

Syntax:

LN(number)
  • number: The positive numeric value for which you want to calculate the natural logarithm.

Examples:

  1. =LN(1)
    Returns 0, because the natural logarithm of 1 is 0.

  2. =LN(2.718)
    Returns approximately 1, because e^1 = 2.718.

  3. =LN(7.389)
    Returns approximately 2, because e^2 = 7.389.

  4. =LN(0.5)
    Returns a negative value, approximately -0.693, as e^-0.693 ≈ 0.5.

  5. =LN(10)
    Returns approximately 2.302, because e^2.302 ≈ 10.

Usage Notes:

  • The number must be positive; otherwise, the function will return a #NUM! error.
  • The function is undefined for non-positive values (i.e., 0 or negative numbers).
  • The LN function is widely used in mathematics, finance, and science, particularly for exponential growth or decay problems, compound interest calculations, and solving for time in natural exponential relationships.
  • For logarithms with other bases, use the LOG function in Excel, which allows specifying a different base.