Toggle a bit in C using XOR

  

int number= 0b11001100;

void setup() {

  // put your setup code here, to run once:

  Serial.begin(9600);

}

void loop() {

  // put your main code here, to run repeatedly:

number ^= 1 << 2;

delay(100);

Serial.println(number,BIN);

}

since we count from zero the 3rd last bit will toggle