Can someone please explain whats going on with Hubble's constant. I understand that to calculate the age of the universe you need to use the relationship; t=1/H. But I don't understand how you get the Hubble's constant into a format that you can use. I've been told that you get a Mpc in Km and divide the Hubble's constant by that value (3.08 exp19). And then put this into the above relationship. But I don't see how this works. Thanks for any help that is offered.