Function finance_math::r72

pub fn r72(rate: f64) -> f64

In finance, the rule of 72, the rule of 70 and the rule of 69.3 are methods for estimating an investment's doubling time. The rule number (e.g., 72) is divided by the interest percentage per period to obtain the approximate number of periods (usually years) required for doubling see definition: https://en.wikipedia.org/wiki/Rule_of_72