1 and 6 add up to 7 and multiply to 6. You know this because to answer this, a person must consider all the factors of 6. Those factors are 1,2,3,and 6. Now, you must consider which pairs (1 and 7; 2 and 3) add up to 7. 2 and 3 add up to 5 and 1 and 6 add up to seven. That would show you that 1 and 6 are your answers.
