Radioactive half-life is a measure of the time required for one half of a radioactive sample to decay into the daughter products. In general, if Y is the amount of a sample that remains, Y is the original sample size, and n is the number of half-lives that have passed,
Example:
Carbon-14 has a half-life of about 3500 years. If a sample starts with 1000 atoms, how many years will it take for the number of atoms to reach 300?