Do you have two brain cells to rub together? What would be the point in= thinking of it in a way incompatible with how everybody speaks? That w= ould only cause confusion.
Let me explain it for the single celled thing on your head:
I give you =A3100. You have =A3100. With me so far?
I walk over to your friend and give him =A3100 twice. He has =A3200. =A3=
200 =3D =A3100 x 2.
No it shouldn't. "mother-in-law" is one word. If there are two such be= asts, you pluralize the whole thing.