Silly question about origin noob help

Ok so I walked through the tutorial level one and found a neat feature. When creating a object like a circle you could start it at the origin with one button press instead of typing 0,0,0. I took a short break from Rhino and have forgot the button.

Anyone know what that button is. THanks

“0” is the shortcut for “0,0”

Thanks a bunch.

0 vs w0:

And when/if you start working with constructionplanes then it is handy to know that 0 is the shortcut to the constructionplane 0,0,0 and w0 is the shortcut to world 0,0,0.