Correct holding posture of pen

The correct way to hold a pen:

The pen is placed between the fingertips of the thumb, forefinger and middle finger, with the forefinger in front, the thumb in the left back and the middle finger in the lower right. The index finger should be lower than the thumb, and the fingertip should be about 3 cm away from the nib. Pen and paper keep 60-degree tilt, palm is empty and round, knuckles are slightly curved.