Decimal multiply(const Decimal& another){
Decimal product;
product.length=length+another.length-1;
product.scale=scale+another.scale;
for(int i=0;i<length;i++)
for(int j=0;j<another.length;j++)
product.digits[i+j]+=digits[i]*another.digits[j];
product.normalize();
return product;
}
