BigNum + x
The + operator creates a new BigNum instance and assigns the result of adding x to it. The x value can be a number, a string, or another BigNum.
Example
x = BigNum.new() + "898923424898234234.8982394"
y = x + x
Note: BigNum:add(x) is more efficient than BigNum + x because it does not create a new instance of the BigNum.