In general algebra, a variable may have different values. But in Boolean algebra only two values of a variable can be "true" or "false" which is expressed by binary 1 or 0 . Thus , in Boolean algebra the values of the three variables a, b and c of the national equation a, b and c can be 1 and 0 . In this case, the rules that Boolean algebras follow in the case of Jaeg are the same - the first three equations follow the rules of general algebra, but there is no similarity in general algebra with the equation 4 1 + 1 = 1 . Thus , the Boolean jag (+) sign does not mean the common + sign. Boolean yag is called Logical Addition or Logical Or Operation . The rules that Boolean algebras follow in terms of multiplication are as follows: Boolean multiplication is called Logical Multiplication or Logical And Operation .