The whole magic jug had 668.36 ounces of mysterious elixir in it.
Sylvia came along and marked it into 4 equal amounts, so each
amount was (1/4) of (668.36 ounces).
Now, you would have us believe, she tucked the magic jug under her cloak,
walked quickly and quietly down the hall into the shadows, pulled the jug out,
and quaffed one of the equal amounts from it, all in one slug.
The quantity remaining in the jug was then
(3/4) of (668.36 ounces) = 501.27 ounces.
The same process works for length, volume, area, stones, money, anything.
If you divide up what you have into 4 equal parts, then each part is 1/4 .
If you eat, sell, lose, or give away 1/4 of it, you have 3/4 left.