My sum is between 7 and 9. I am not a double. I am not a double plus one. Who could I be?

Question

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Answer 1

between 7 and 9 is 8

4+4 = 8 but that's a double 8 = 4 x 2

that leaves

5+3, 6+2, 7+1, 8+0 if you're restricted to non-negative integers, 8 is a double. 7 = a double + 1 = 3(2)+1 6 is a double.

5 is a double plus 1 = 2(2)+1 = 5

that eliminates all the possible answers

worst answers are 4+4 or 8+0

if you allow negative integers

then infinitely -more possibilities are: -1 +9, -2 + 10, -3 + 11, -4 + 12, ...-n + n+8 ...

eliminate the doubles

leaves: -1+9, -3+11, -5+ 13, ...

the 9, 11, 13, ... part of the sum though are all a double plus 1

that leaves none

allow non-integer possibilities adds in another infinite number of possibilities

4 1/2 + 3 1/2 = 8

neither is a double term neither is a double + 1

4 1/2 isn't double 3 1/2