void setup() {
  Serial.begin(9600);
}

void loop() {
  float x = -1.5;//num
  float *xp = &x;//adding the address of x to a pointer named xp
  uint32_t *ip = (uint32_t) xp;//we create another pointer that will actually print the value
  //it's a 32 bit unsigned integer cause to access the raw binary representation of the floating-point number.
  Serial.println(*ip,BIN);//then we just print the value in binary
  while(1);
}