Tell you a calculation method, according to the width of 700 mm per person as the standard, 20 people need 20*0.7=14 meters, which is the circumference of the round table, divided by 3.14 is 4.46 meters, take an integer, 4.5 meters. 0.7 meters refers to a chair with armrests, and those without armrests can be calculated by 0.5 meters.