public static BigInt operator *(BigInt a, BigInt b)
{
BigInt temp = new BigInt(a), sum = new BigInt();
for (int i = 0; i < b.number.Count; i++)
{
temp = temp.MultOnDigit(b.number[i]);
temp = temp.MultOn10Pow(b.number.Count - i - 1);
sum = sum + temp;
temp = new BigInt(a);
}
if (sum != new BigInt(0))
{
sum.Sign = a.Sign * b.Sign;
}
else
{
sum.Sign = 1;
}
return(sum);
}