The columns labeled "Fraction remaining" and "Percentage remaining" in the chart measure the "amount of material that has not decayed" over time. Each entry shows how much of the original material is still present (not decayed) as half-lives elapse.
- After 0 half-lives, there is no decay, so the "Fraction remaining" is [tex]\( \frac{1}{1} \)[/tex] or 100%, indicating all of the material is still present.
- After 1 half-life, the material remaining is halved, so the "Fraction remaining" is [tex]\( \frac{1}{2} \)[/tex] or 50%.
- After 2 half-lives, the remaining material is quartered, so the "Fraction remaining" is [tex]\( \frac{1}{4} \)[/tex] or 25%.
- This pattern continues with the "Fraction remaining" and "Percentage remaining" decreasing by half with each subsequent half-life.
Thus, the value being measured in these columns is the "amount of material that has not decayed."
