logarithms

• How to Calculate a Logarithm Without a Calculator
  Use logarithm laws for exact values, estimate by powers and familiar logs, or apply a convergent series to calculate logarithms by hand.
• How to Find an Antilog on a Simple Calculator
  To find a common antilog, enter the exponent into 10^x, often SHIFT or 2nd plus LOG. For another base, calculate that base to the exponent.
• How to Find the Inverse of a Sigmoid Equation
  Invert the standard logistic sigmoid by taking the log-odds: x = ln(y/(1−y)). This guide derives the formula, its domain, and scaled variants.
• How to Solve the Continuous Compounding Formula for r
  Rearrange the continuous-compounding equation A = Pe^(rt) with a natural logarithm to find the rate r from principal, final amount, and elapsed time.