The 56 = 7 x 8 are consecutive number 5, 6, 7, 8. So, 7x8 equals 56. (This only works for two facts - 1, 2, 3, 4 is 12 = 3x4 and 5, 6, 7, 8 is 56 = 7x8)
You took 7 friends to get lunch and you paid for everyone’s meal. They each ordered the same thing which was 8 dollars (-8). In total you owe 56 dollars but because you haven’t paid it yet it would be -56 dollars.
