Glossary · Phase 2 · Math, when you need it
Natural logarithm
The log that undoes e to a power: ln(x) asks "e to what power gives x?" So ln(e) is 1 and ln(1) is 0.
Try it now
eˣ and ln x are mirror images across the diagonal line: each one undoes the other. Notice eˣ is always above zero, and ln x only exists for x above zero.
Learn it properly
Exponentials and logarithms · Growth, decay, and why logs turn products into sums. About 25 minutes.
Other terms from the same lesson
- exponential: Growth by repeated multiplying, like doubling every step.
- logarithm: The reverse of an exponential: how many times you multiply to get a number. log₁₀(1000) is 3.
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