Spanish to English Science Mathematics & Statistics

I also posted "raíz por defecto". When estimating the square root of an imperfect square, the raíz por defecto and raíz por exceso are the square roots of the closest perfect squares.

Example:
42 is an imperfect square.
The closest perfect squares are 36 and 49.
Their square roots are 6 and 7.
So 6 is the raíz por defecto and 7 is the raíz por exceso.

Any ideas? I've found this referenced as "excess and deficiency" only in texts about ancient Chinese math techniques and really bad translations.

TIA!!