Is extension a scalar or vector quantity?

Scalar quantity has only magnitude , but no direction while vector quantity has both magnitude and direction.You can understand it by comparing speed and velocity.Velocity has magnitude of speed in a particular direction (or say displacement/time take) while speed only defines the rate of distance covered (no direction).

If you are still unable to get your answer for your question then please, elaborate or give some description of extension.

-Ajlan Wasfi Khan