[Gimp-developer] Multiply blend mode in GIMP

[Calculemus <calculemus1988 gmail com>]

I am reading this: docs.gimp.org/en/gimp-concepts-layer-modes.html

and I wonder why is the formula for "Multiply", E = (M * I) / 255?

Why divide with 255, that is the part that confuses me.
Should it not be just M * I and then clamp the result in range 0 to 255?

Thanks