Tie 7 cylindrical objects side by side and find out how long the rope is. It is known that the diameter of each circle is 1 cm.

if it's a long line like that, it's easier to calculate.

just add 12 diameters to the circumference of a circle.

it is 1*3.14+12*1=151.4 cm.

in real life, it's all tied up like the picture below.