Many things are equivalent to 400 meters. You can use any of the SI prefixes to change the meters. For example: 400 meters = 0.4 km (or kilometers) or 400 meters = 400,000,000 micrometers
You can also change this to imperial. 1 meter = 1.0936 yards so 400 meters = 437.44 yards
In order to get the “correct” answer you first need to know the unit you are converting the meters into.