+ when you see the -you can evaluate + - end when you reach the end of the expressionyou can evaluate - you can' evaluate the + until you see what operator follows the if it' or you need to wait before applying the sign until you've evaluated the or howeverin this example the operator following the is -which has the same precedence as +so when you see the you know you can evaluate + which is the then replaces the + you can evaluate the - when you arrive at the end of the expression figure shows how this looks in more detail notice how you go from left to right reading items from the inputand thenwhen you have enough informationyou go from right to leftrecalling previously examined input and evaluating each operand-operatoroperand combination because of precedence relationshipsit' bit more complicated to evaluate + * as shown in table table evaluating + * item read expression parsed so far comments + + can' evaluate + because is higher precedence than + * when you see the you can evaluate *