So if you had a sample of radioactive Harmytonium-126 and these conditions:
(where H(t)=how many moles of Harmytonium are left at time T)
Then you’d know that the rate was 8%?
Edit: Oh, never mind, the rule of 72 is for annual compounding/decaying. Apparently, for continuous decay/compounding, it’s the rule of 69. eh.