Logistic

I wasn't sure if this is feasible at excel bec. I asked one computer expert and he said that it doesn't work and that I will need to buy a specific program that will calculate automatically any decay constancy for any isotopes. But since you do you know, perhaps you can guide me on what formula to use on excel and hopefully figure out the rest. I am not so much into computer worksheet. As a matter of fact, I just started excel program last few days ago but couldn't spend time much on this because of work and family issues. So if you or anybody can help, I'll appreciate it very much. Thanks.

Does anybody know how to create a worksheet using the excel program with the decay constancy formula of A=Ao e -(0.693t/T1/2) ?