Subject: Easy formula to calculate attraction of 2 magnets

I would like to do a rough simulation on the attraction between 2 magnets.
Like, with the distance between the magnets given I'd like to calculate
how strong they attract each other (and lets say both magnets are equal).
The problem is: I have no idea about the corresponding formula ... and
those starting with integrals are a bit tough for me to understand. 

Is there an easy formula for my problem if it is kept to the basics like 
described above?

What would change in that formula if there would be some object 
in between of those magnets shielding them (conductor plates or so)
in the sense of

    

Is this still something one can simulate oneself or does one have to buy
a serious simulation software?

Thanks for your answer

René

Re: Easy formula to calculate attraction of 2 magnets