Henry Ernest Dudeney/Modern Puzzles/170 - A Heptagon Puzzle/Solution

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Modern Puzzles by Henry Ernest Dudeney: $170$

A Heptagon Puzzle
Using the fourteen numbers, $1$, $2$, $3$, up to $14$, place a different number in every circle
so that the three numbers in every one of the seven sides add up to $19$.
Dudeney-Modern-Puzzles-170.png


Solution

The diagram shows the solution.
Dudeney-Modern-Puzzles-170-solution.png
Starting at the highest point, write the numbers $1$ to $7$ in a clockwise direction at alternate points.
Then, starting just above the $7$, write $8$ to $14$ successively in the opposite direction, taking every vacant circle in turn.
If instead you write in $1$, $3$, $5$, $7$, $9$, $11$, $13$ and then $2$, $4$, $6$, $8$, $10$, $12$, $14$,
you will get a solution with the sides adding to $22$ instead of $19$.
If you substitute for every number in these solutions its difference from $15$ you will get the complementary solutions,
adding respectively to $26$ and $23$ (the difference of $19$ and $22$ from $45$).


Sources