19 + 23 + 518 = 560
The sum of 712 plus 518 is 1230
672.72 repeating
672.72 repeating
The sum of -80 and 77 is -3
-15.4
12 + 77 = 89
that's kinda general. it could be 518 and 1. are you sure its sum? or is it product?
If sum of digits of a number is divisible by 3 then the number is divisible by 3. Sum of digits = 5+1+8 = 14 and 14 is not divisible by 3. So 518 is not divisible by 3.
38 + 39 = 77
99
The numbers 40.5 and 36.5 have a difference of 4 and a sum of 77.