Aroller coaster train with 666 passenger cars and the front decoration has a mass of 3{,}500\,\text{kg}3,500kg3, comma, 500, start text, k, g, end text. when the train has the front decoration and only 444 passenger cars, it has a mass of 2{,}400\,\text{kg}2,400kg2, comma, 400, start text, k, g, end text.