The crossword solution for the term 'PI, FOR INSTANCE' is the word 'RATIO'. A RATIO is a mathematical comparison of two or more values. It is typically expressed as two numbers separated by a colon, such as 1:2. Ratios are used to compare quantities in different units, such as miles to kilometers, or to compare parts of a whole, such as the number of boys to girls in a classroom. The term 'PI, FOR INSTANCE' is referring to the mathematical constant pi, which is the RATIO of a circle's circumference to its diameter.