Since positives are greater than negatives, greatest product will be positive, least will be negative.
Let the integers by x and y.
Then: xy = 18 and the positive factors of 18 are (1, 18) or (2, 9) or (3, 6)
It would seem that the least sum of x + y = 3 + 6 = 9
However, both x and y can be negative to get a product of +18!
So, the negative factors are (-1, -18) or (-2, -9) or (-3, -6).
And we see the least sum is -1 -18 = -19
