..yes i know they have different strand numbers,like 16-20 etc..
what is a good amount of strands,the more or less?????

That depends on what you are looking to get out of your bow. Since there are so many string materials currently being marketed it is difficult to make blanket statements. However, if we take any specific string material then we could say that fewer strands would probably produce a faster arrow. While a string with more strands would probably last longer as there is more material to absorb normal wear and tear.

also the material matters, there are different diameter materials, some require more strands to get an equal string.

--Bob

I guess I never really answered your original question. 18 strands is probably the most common size that I have seen though, again, that depends in large part on the material utilized.