If the five-digit number 8X357 is divisible by 11, then what is X?
To be divisible by 11 we must have that either
8 - X + 3 - 5 + 7 = 0 simplify
13 - X = 0
X = 13 [ impossible ]
or
8 - X + 3 - 5 + 7 = 11 simplify
13 - X = 11
X = 2
Check 82357 / 11 = 7487
