contract Randomish {

    uint public constant MAX = uint(0) - uint(1); // using underflow to generate the maximum possible value
    uint public constant SCALE = 500;
    uint public constant SCALIFIER = MAX / SCALE;
    uint public constant OFFSET = 100;


    // generate a randomish  number between 100 and 600.
    // Warning: It is trivial to know the number this function returns BEFORE calling it.

    function randomish() public view returns(uint) {
        uint seed = uint(keccak256(abi.encodePacked(now)));
        uint scaled = seed / SCALIFIER;
        uint adjusted = scaled + OFFSET;
        return adjusted;
    }
}