[Math] Calculate the overall chance of something happening in a trial

Question

I've searched everywhere for an answer but couldn't find a formula to use.
I have an independent event that has a 1% chance of happening every second. In my trial, there are 30 seconds. How can I calculate the overall chance of this event happening?

Thanks.

Answer 1

$$\eqalign{P(\hbox{event happens at least once}) &=1-P(\hbox{event does not happen})\cr &=1-(0.99)^{30}\ .\cr}$$