Question

Samantha's teacher wrote the numbers 10,-2,4,-1,-7 ,1 on the smart board. The teacher asked which number should she write in order to make the sum of all the numbers equal to zero

Answer 1

I think that the answer is 5. But,it could be some thing else

Answer 2

Let the unknown addend be x.  

Sum up the given numbers {10,-2,4,-1,-7 ,1}:  8 + 3 - 6 = 11-6 = 5

Then 5 + x = 0 and x = -5