Right-- it's basically just conversion factors which are composed of equivalencies like "1 in = 2.54 cm" only written as convenient FRACTIONS in order to convert units and quantities all at once.
Basically,
.25 in X (2.54 cm/ 1 in) = ____ in (because a quantity which appears in both numerator and denominator is able to be canceled as it is always equal to "one" or some similar logic)
the same factor would be flipped the other side up (that is 1in/2.54 cm) if one were using it to convert centimeters to inches.
The real magic, of course, is when you use a long string of them-- which is what I did with the Henrietta-the-Chicken problem for my DD.
