Binary Manipulation in arduino with 74HC595
I ended up using jsotola suggestion, so the code works

int latchPin = 11;
int clockPin = 9;
int dataPin = 12;
int dt = 2000;
uint8_t n1 = 128, n2 = 1;
byte myByte = 0b10000001; //in BIN

void setup() {
Serial.begin(9600);
pinMode(latchPin,OUTPUT);
pinMode(dataPin,OUTPUT);
pinMode(clockPin,OUTPUT);
}

//circular shift to the left
void loop() {
digitalWrite(latchPin,LOW);
shiftOut(dataPin,clockPin,LSBFIRST,myByte);
digitalWrite(latchPin,HIGH);
int i;


myByte = 0b10000001; //restarting the value of 129
        Serial.print("BIN: ");
        Serial.print(myByte,BIN);
        Serial.print(" --&gt; ");
        Serial.print("HEX: ");
        Serial.print(myByte,HEX);
        Serial.print(" --&gt; ");
        Serial.print("DEC: ");
        Serial.println(myByte,DEC);
        delay(200);


    for (int i = 0; i &lt; 7; i++) {
        Serial.print("i:  ");
        Serial.println(i);
        //int i1 = i+1;
        //int myGap = myByte - (pow(2,i));      //no need to round when it's raised to 0;
        //int firstpart = (myGap/2);
        //int secondpart = 0.5 + pow(2,i1);     //because it rounds the number. (i.e --&gt; 1.9999 = 1)
        //myByte = firstpart+ secondpart;

          myByte = (myByte - (pow(2,i)))/2 + (0.5 + pow(2,i+1));


        Serial.print("BIN: ");
        Serial.print(myByte,BIN);
        Serial.print(" --&gt; ");
        Serial.print("HEX: ");
        Serial.print(myByte,HEX);
        Serial.print(" --&gt; ");
        Serial.print("DEC: ");
        Serial.println(myByte,DEC);
        digitalWrite(latchPin,LOW);
        shiftOut(dataPin,clockPin,LSBFIRST,myByte);
        digitalWrite(latchPin,HIGH);
        delay(100);
    }

}


Anyway other suggestion are welcome.