Factors of 56 are: 1, 2, 4, 7, 8, 14, 28, 56
Factors of 84 are: 1, 2, 3, 4, 6, 7, 12, 14, 21, 28, 42, 84
The outside term multiplies by the outside term on the oposite side to equal the answer.
Example:
Look at the factors of 84
84X1=84
2X42=84
3X28=84
and so on!