6 numbers their sum is 20. (You can't use fractions,decimals or repeat any number)

My solution (Not sure if it is correct, can you find another :D?

0,6,5,4,3,2

I think that is the only correct answer since some of 1-6 is =21. Can we use Negative Numbers?

How about

19, -19, 63, -65, 2, 20

Nice!!

That's good idea melody!

But, I think Integers (Positive only is allowed)

Yes the question implies integers but integers can be negative.

I assume you are right but I was demonstrating the need for precise language and instructions when dealing with mathematics.