66. Communication. An army column 40 km long travels 40 km. How many kilometers will the communication officer travel, sent with a package from the rearguard to the vanguard and returning back?
66. The distance traveled by the messenger is equal to the square root of twice the square of 40, added to 40, which amounts to 96.568 km, or approximately \(96 \frac{1}{2}\) km.