How do you calculate half life?

To calculate half of a life, you will first need to know how long the whole life is. If a person lived to be 80, then half of that life would be 40. You will just divide the age at which the person or animal died, by two.
Q&A Related to "How do you calculate half life?"
 1. Solve for the natural logarithm, or the "LN, of 1/2. This expresses that 50 percent of the original amount of the isotope has decayed. 2. Find the rate of decay for the isotope http://www.ehow.com/how_8589002_calculate-halflife...
 Check the time between your first decay rate and when the decay rate reaches half this number. http://wiki.answers.com/Q/How_do_you_calculate_hal...
 it takes 713 million years for half of the U235 to decay to lead-207. half-lives: 1 = 50% U235 . & 50% lead-207. 2 = 25% U235 & 75% lead-207. 3 = 12.5% U235 and 87.5% lead http://answers.yahoo.com/question/index?qid=200903...
 1 Learn to bunny hop. There are many good how-to videos on YouTube. Follow the steps to making good bunny hops. Take a few days to get used to it. It might actually take a few weeks http://www.wikihow.com/Improve-at-Half-Life-2-Deat...