Natural log

Math

Definition

The natural logarithm (ln) is the logarithm with base e, where e ≈ 2.71828. It answers the question: to what power must e be raised to get a given number?

Examples

  • ln(e) = 1 because e¹ = e
  • ln(1) = 0 because e⁰ = 1
  • Finding the half-life of a radioactive substance using ln(2)
Key Fact

ln(e) = 1, ln(1) = 0, ln(eˣ) = x, e^(ln x) = x

Related Terms

Logarithm properties Solving log equations Exponential growth and decay

Study This Concept

Practice natural log with free review games in these units:

Pre-Calculus Unit 3: Exponential and Logarithmic Functions