"'Serial' does not name a type" error I'm getting a "'Serial' does not name a type" error when this program is compiled. I need for the 8 channels of voltage to be displayed. I'm sure it's a simple fix, however I'm still learning Arduino programming. I thank you for your help. 

int pin_Out_S0 = 8;
int pin_Out_S1 = 9;
int pin_Out_S2 = 10;
int pin_In_Mux1 = A0;
int Mux1_State[8] = {0};
//float Mux1_State[i] =0;
int RawValue=0;
float Voltage = 0;
void setup() {
  pinMode(pin_Out_S0, OUTPUT);
  pinMode(pin_Out_S1, OUTPUT);
  pinMode(pin_Out_S2, OUTPUT);
  pinMode(pin_In_Mux1, INPUT);
  Serial.begin(9600);
}

void loop() {
 RawValue = analogRead(pin_In_Mux1);
 Voltage = (RawValue * 5.0) / 1024; //scale the ADC
  updateMux1();
  //Serial.println(Mux1_State);
  for(int i = 0; i &lt; 8; i ++) {
    if(i == 7) {
      Serial.println(Mux1_State[i]);
    } else {
      Serial.print(Mux1_State[i]);
      Serial.print(",");
      //vout = (value * 5.0) / 1024.0;
    }
  }
}

void updateMux1 () {
  for (int i = 0; i &lt; 8; i++){
    digitalWrite(pin_Out_S0, HIGH &amp;&amp; (i &amp; B00000001));
    digitalWrite(pin_Out_S1, HIGH &amp;&amp; (i &amp; B00000010));
    digitalWrite(pin_Out_S2, HIGH &amp;&amp; (i &amp; B00000100));
    Mux1_State[i] = analogRead(pin_In_Mux1);
  }
}
Serial.print("Raw  Value = " );
Serial.print(RawValue);
Your last two lines are not in any function. This confuses the compiler. You need to move those two statements inside a function.

Because those statements refer to RawValue, I'm guessing you want to put them in loop(), where RawValue is being updated.

Also, remember that the IDE will tell you on which line the error is, which is helpful when debugging compilation errors.