Puzzle -If you are good in maths

[Nitish]

I dont think the question is written out very well...
Unless I just simply don't understand it.

"Breaks apart a 40KG stone into 4 pieces in such a way that using those 4 parts anyone can weight 1KG to 40KG each weights."

Well, that's not right for a start. If one of those 4 pieces weigh 40KG, then where are the other 3? lol
Can't A B C and D all be 10KG's making 40KG ?

I don't know, I just don't get it.

Its common sense that none of them can be 40kg or anything over 37kg also.
You gotta make 4 such weights so that if you add or subtract any weight then you can get any weight from 1-40kg. Try with the answer which i supplied above.

---------- Post added at 10:44 PM ---------- Previous post was at 10:42 PM ----------

A = 6.285
B = 10.571
c = 15.857
D = 7.285

All of them have to be integer weights. Also, if you disregard this rule, you cannot get 2KG out of these weights ( and many more. I just checked for 2).