The way to arrange the sacks of flour is as follows:--2, 78, 156, 39, 4.
Here each pair when multiplied by its single neighbour makes the number
in the middle, and only five of the sacks need be moved. There are just
three other ways in which they might have been arranged (4, 39, 156, 78,
2; or 3, 58, 174, 29, 6; or 6, 29, 174, 58, 3), but they all require the
moving of seven sacks.
[Illustration]
[Illustration]