18. Bumblebee flew from Cybertron to Pandora, originally planning to travel at a speed of 600,000 kilometers per hour. However, during the journey, he encountered an electronic storm, and only half of the distance could be traveled at the planned speed, while the remaining distance was traveled at a speed of 400,000 kilometers per hour. As a result, he arrived at Pandora 1 hour later than planned. The distance from Cybertron to Pandora is $\qquad$ million kilometers.
$240$