Yeah the Title says it all I need to know how many stamps I need to send a letter from here ( Cali ) to Western Australia... Or if I need like a special stamp or anything Thank you

The first envelope contains a photo the size of the envelope. How many 41 cent stamps do I need? The second manila envelope contains 2 empty manila envelops. How many stamps should I put on the exterior envelope? If I wanted to use 37 cent stamps instead, would I need to put just one more then the amount of 41 cent stamps it takes? Thank you very much!

I know that stamps have an invisible ink that glows under ultra violet light, and thats how it tells if you got a real postage stamp on it. The automated machines it slides down reads stamps and address. But how does it tell you have the correct amount in stamps? You know, lets say I put on a 37 cent stamp instead of 39 cents, or lets say I put an old 31 cent stamp and a bunch of 2 cent stamps to equal the 39 cents. Does each demonination have different color invisible ink or something to match the amount?

I'm writing a letter to my friend and I was wondering how many stamps I would need to send it from Ohio to Arizona. It's not going to weigh much at all. Thanks!