Why the different handling of "mas":

Is this a rule or an exception?

Any other example?

I want more postcards of Mexico
- quiero mas postales de Mexico

Versus

I have four more postcards
-tengo cuatro postales mas

Question

Why the different handling of "mas":

Is this a rule or an exception?  

Any other example?

I want more postcards of Mexico
- quiero mas postales de Mexico

Versus

I have four more postcards
-tengo cuatro postales mas

anonymous · Answer

I was just being lazy about the tilde, but question is why mas is before postales in the first instane and after in the second?

anonymous · Answer

In the first example, there isn't a specified number of postcards. 

In the second example, there is a specified number: four.

anonymous · Answer

I still do not how to give medals :(

anonymous · Answer

Oh really? You just click on Best Answer, next to the answer you think is best. That's all. Thanks!