For some reason my math just returns 0. The value are set, I have checked.
int currentSize = 4079;
int totalSize = 500802;
int percentage = ((currentSize/totalSize) * 100);
The problem, as other have pointed out, is integer division will turn anything less than 1 to zero. This happens before multiplying by 100. You can change the order of operations to get something better:
int percentage = currentSize * 100 / totalSize;
If you are concerned about rounding, you can use
int percentage = (currentSize * 100 + (totalSize >> 1)) / totalSize;
These avoid the expense of working with double or float values.