The previous provided solution is not correct. Since, the order doesn't matter when you add (commutative property if you want to be fancy), this is a combination problem, not a permutation problem (if you are not familiar with these terms, see solution #2 below)
We have 6 total numbers.
How many sums can be made picking out any 2 numbers? 6C2 = 15 (same problem as "total number of handshakes in a company of 6 people)
Total possible sums by picking out any 3 numbers: 6C3 = 20
4 numbers: 6C4 = 15
5 numbers: 6C5 = 6
6 numbers: 6C6 = 1
So, the answer is 15 + 20 + 15 + 6 + 1 = 57
Solution #2 (for those in earlier grades who don't know how to calculate 6c3 yet)
You either use a number or you don't: that's 2 options for each number.
So, this a fundamental counting problem
2 × 2 × 2 × 2 × 2 × 2 =
= 64
The condition of the problem is " By adding 2 or more different numbers from this set"
So we we have to take away:
when we don't use any of the numbers, "no" for each number:
0 1 2 4 8 16
no no no no no no (that's 6C0 btw in solution #1)
1 total sum
when we don't use each number once. That's 6 obviously.
6 total different sums
So we we have to take away: (6+1 ) from 64
Answer: 57