"=$B1*INDEX(A:A,ROW())"

See this absolute bullshit right here?

This fucking cunt of a problem designed by some dippity-do finger-painting fucking jackass at google doesn't work why?

Because for some *god damn reason* they decided it would be a good idea to setup it up in a way that when you use absolute cell references in a formula, you can't use functions in the formula too. No the other side has to be a literal or cell reference apparently.

Motherfuckers.