Definition
Rule
A mathematical rule is a precise instruction or relationship that determines an output or result.
What it means
A rule tells what to do or how two mathematical things are connected. Test it on every given case. If it fails even one case where it should work, it is not the rule for that task.
Remember it
A rule must work every time it is supposed to.
Example
Use the rule “double the input, then subtract 3.” An input of 5 gives 2 × 5 − 3 = 7, and an input of 9 gives 2 × 9 − 3 = 15.
Watch for
This card owns the mathematical pattern and input-output sense of rule, not classroom rules, game rules, laws, or policies.
Common mix-up
A guess that fits one example is not enough; the rule must agree with every stated input, term, or figure.
Exact meaning
A mathematical rule is a precise instruction or relationship that determines how values, figures, or sequence terms are produced from permitted inputs or earlier information.