If the sepals, petals and stamens, or their united bases (floral tube), arise from below the ovary it is superior. If the sepals, petals and stamens are free from each other the flower is hypogynous (compared with perigynous and epigynous.
In a floral formula a superior ovary is often depicted as follows, e.g. G (3) _. To remember whether the line goes above or below the number it can be useful to consider the number represents the ovary and the line as the point of attachment of the other floral parts.
Illustration from Clarke, I. & Lee, H. (2003) Name that Flower, Melbourne University Press, Victoria.