William C. answered 11/24/23
Experienced Tutor Specializing in Chemistry, Math, and Physics
Every half life the fraction Nf/N0 gets halved.
The fraction is 1/2 after 1 half life, 1/4 after 2 half lives, and so on...
Nf/N0 = (1/2)n where n = the number of half lives.