You could try counting in base 561/3 = 3.825862 (approx).
It equals 24.
96
It doesn't ! -7 plus -5 equals -12 ! -7 plus 5 equals -2
If I am correct, 9 plus 7 equals 112.
89
Well, darling, 1000 divided by 7 is approximately 142.857. So, technically, 142.857 times 7 equals 1000. But hey, who's counting?
500,500
1000 + 7 = 1007
1000
35
28
144