Examples of values that cannot be suffixed with ether units

EtherUnitsInvalid.sol

// SPDX-License-Identifier: GPL-3.0
pragma solidity ^0.8.0;

contract EtherUnits {

    function notWorking() public {
        uint256 total;

        // TypeError: Hexadecimal numbers cannot be used with unit denominations. 
        // You can use an expression of the form "0x1234 * 1 day" instead.
        uint256 a = 0x05 ether;

        // ParserError: Expected ';' but got 'ether'
        uint256 b = total ether;
    }

}