standard_description: Identify zeros of polynomials when suitable factorizations are available, and use the zeros to construct a rough graph of the function defined by the polynomial.
problem_activity: Task
Nina was finding multiples of 6. She said,
18 and 42 are both multiples of 6, and when I add them, I also get a multiple of 6: $$18+42 = 60.$$
Explain to Nina why adding two multiples of 6 will always result in another multiple of 6.


aligns: no