docs: public QrCodeEncoder addNumeric(byte[] numbers) {
  		for (int i = 0; i < numbers.length; i++) {
  			if (numbers[i] < 0 || numbers[i] > 9)
  				throw new IllegalArgumentException("All numbers must have a value from 0 to 9");
  		}
  
  		StringBuilder builder = new StringBuilder(numbers.length);
  		for (int i = 0; i < numbers.length; i++) {
  			builder.append(Integer.toString(numbers[i]));
  		}
  		MessageSegment segment = new MessageSegment();
  		segment.message = builder.toString();
  		segment.data = numbers;
  		segment.length = numbers.length;
  		segment.mode = QrCode.Mode.NUMERIC;
  
  		segment.encodedSizeBits += 4;
  		segment.encodedSizeBits += 10*(segment.length/3);
  		if( segment.length%3 == 2 ) {
  			segment.encodedSizeBits += 7;
  		} else if( segment.length%3 == 1 ) {
  			segment.encodedSizeBits += 4;
  		}
  
  		segments.add(segment);
  
  		return this;
  	}