Mulscale

mulscale <Result> <Value 1> <Value 2> <Value 3>

Equals the following series of commands:

set <Result> <Value 1>
mul <Result> <Value 2>
shiftr <Result> <Value 3>

The main difference is that the calculation uses 64 bits to prevent overflow, while using gamevars for intermediate values would limit it to 31 bits.

One example of where this limitation takes places is with rotatesprite scaling, where 320*65536 scaled with statusbarscale is dangerously close to 31 bits.