## Lines Through Dots

 ```o o o o o o o o o``` ` ` ```o o o o o o o o o o o o o o o o``` ` ` ```o o o o o o o o o o o o o o o o o o o o o o o o o``` ` ` ```o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o```

First, a classic:

1. Without lifting your pencil, draw four straight lines through 9 dots arranged in a 3x3 grid.

Now the extensions. Without lifting your pencil, and trying to begin and end at the same location,

1. Draw six straight lines through 16 dots in a 4x4 grid.
2. Draw eight straight lines through 25 dots in a 5x5 grid.
3. Draw ten straight lines through 36 dots in a 6x6 grid.

Source: Many puzzle sources.  Can you do it with fewer lines?

Solutions were received from Alan O'Donnell, Joseph DeVincentis, Philippe Fondanaiche, Kevin Haborak, and David Bachtel.  Thank you to those who pointed out Ed Pegg's discussion on this topic at http://www.mathpuzzle.com/dots.html.  The solutions below are taken from that page (some answers on that page are from JD above.)    Mail to Ken