public void AddTo(BigNumber num)
{
if (num.Sign != this.Sign) {
int compare = num.CompareAbsolute(this);
if (compare < 0) {
AbsoluteSubtractFrom(num, this);
this.Sign = num.Sign;
} else if (compare > 0) {
AbsoluteSubtractFrom(this, num);
this.Digits = num.Digits;
} else {
this.Clear();
this.Sign = enumSign.Positive;
}
} else {
AbsoluteAddTo(num);
}
}
