Puzzle 6, 21 (Blackjack)
21 Hook:
The game is about getting as close to 21 as possible without going over.
Original Idea:
Corin Anderson
Puzzle Location:
Fremont Park
Presentation:
Each team arrives to a dealer at a blackjack table at the park. They are encouraged to sit down and play.
Posted is
this sign:
BANG Blackjack
Minimum Bet ....... 2
Maximum Bet ...... 2
Bailout Money ........ 3
Win Pays ............ 5
Blackjack Pays .... 7
The dealer has a rack of chips in front of him, in the denominations 1, 5, 10, and 21.
Players receive starting money to start, and play blackjack. If they do not have enough money to bet, they can ask for a bailout, which will give them 3 more. Each team can only have one player at a time.
Teams should figure out two things pretty quickly:
Procedure notes for the dealer:
 Deal to all players first, then hole card, then second player cards, then up card.
 Then dealer should check for blackjack.
 Stand on all 17s, including soft.
 Fancy stuff like splits, doublingdown, surrender, and insurance are allowed, but only if the player asks.
 Splits: As normal per Vegas rules.
 DoublingDown: As normal per Vegas rules.
 Surrender: Normal (player loses half the bet).
 Insurance: Player does side bet of 2; insurance pays 4.
 If the player has blackjack and the dealer doesn't, don't play out the hand.
Puzzle Answer:
VINGTETUN
Puzzle Solution:
The stickers are:
 Twos: V
 Threes: ING
 Fours: M
 Fives: TE
 Sixes: ER
 Sevens: T
 Eights: ION
 Nines: AT
 Tens: P
 Jacks: LE
 Queens: ST
 Kings: NT
 Aces: UN
 Chip Ones: TO GET ALL THE TIPS, COLLECT ALL FOUR CHIPS.
 Chip Fives: IT'S USEFUL TO KNOW THAT ACES AREN'T LOW.
 Chip Tens: THE LETTERS YOU MINE WILL FILL IN THIS LINE: _ _ _ _ _  _ _  _ _
 Chip TwentyOnes: THE LAST STEP'S NOT HARD: USE EVERY PRIME CARD!
Putting the primevalued card letters (two, three, five, seven, Ace) in the blanks gives the answer.
WeiHwa's Notes:
Surrender was taken once the whole weekend, and doubling down was done only occasionally. There was an interesting fourhand split (that ended up not being very profitable for the player). We found ourselves repeating the same phrases over and over, to the point where Jan and I still giggle at "The minimum bid is two, sir."
The puzzle is nighimpossible to solve if you don't notice the backs of
the chips. To help this, teams were asked "would you like to change up
to a 10?" when they had two 5 chips. Teams that pondered the purpose
of this strange question figured out what it was getting at. In a few cases, a team would harvest all the card letters, decide they were done playing, and walked away without ever looking at the back of a chip. In those cases, we told the team that we would save their winnings in case they decided to revisit us.
The blackjack sign (with the EasterEgglike humorous photograph) was put on the prize table on Sunday. I don't know who took it.
Puzzle 7, 21 equals
21 Hook:
There are 21 ways to have three unordered operators, if you allow "no solution".
Original Idea:
Ian Tullis
Puzzle Location:
Jack W Lyle Park
Presentation:
Teams receive two lettersized pages of paper (
1,
2).
Puzzle Answer:
SIGN
Puzzle Solution:

Realize (from examples) that the goal is to put the given numbers in the squares, and then add operators so that the expression evaluates to the magic number. Rules at bottom say parentheses aren't allowed.

Realize that the magic number is always 21.

Solve many such things.

Decode each set of operators to a letter, as per the example, using the table at the right.

Extract message FINDALLFOURSOLUTIONSFORONEONEEIGHTTHIRTEEN.

The solutions for {1,1,8,13} are 13+8+11, 13+8/1/1, 13+8*1/1, 13+8*1*1.

Those letters are G, I, N, S.

Anagram (as per rules) to get SIGN (as confirmed by text).
WeiHwa Comments:
It turns out that it's very hard to find a set of numbers with more than three solutions, even more so when you realize that you can't use any numbers that contain the letters V, W, or X (approximately 40% of all integers). Ian had the idea, but I did all the numbercrunching.
Puzzle 8, Meta
21 Hook:
The smallest way to build a square out of smaller squares of distinct size  "
Squaring the Square"  requires 21 squares.
Original Idea:
WeiHwa Huang
Puzzle Location:
Nealon Park
Presentation:
Teams receive:

21 squares of different sizes (1, 2). The top and bottom of the squares have green, the left and right have blue. Each square has a number that represents its side length, and a symbol at the top corresponding to one of the other puzzles.

21 convex quadrilaterals (3). The corners are colored alternating green and blue, and the diagonals are drawn connecting opposite corners. A number is at the intersection of the diagonal.

A large 10x10 inch square grid (4), clearly to put the squares on. The 33 (upperleft) square is given faintly. There are numbers printed next to the edge.

A large diamond (5), with a dottedline border, and green and blue dots at opposite corners.
Puzzle Answer:
YOU
Puzzle Solution:
 Assemble both grids, the "square" grid (solution) and the "quad" grid (solution). This is greatly helped by noticing the correspondence between the two grids, as shown in the example:
 Each square has a matching quad, and vice versa; they will both have the same number.
 Each square has a number corresponding to its side length.
 Each quad has four corners; two green and two blue/purple. The opposite corners have the same color and the diagonal is drawn. The number on the quad is at the intersection of the diagonals, simultaneously "marking" both diagonals.
 When multiple squares on the "square" grid meet, they share an edge which is both the sum of the squares on one side of the edge, and the sum of the squares on the other side of the edge.
 When multiple quads meet at a corner, the unified corners form a circle. The quad diagonals going into that corner have the property that the sum of the upper diagonals equals the sum of the lower diagonals (for green), and sum of the left diagonals equals the sum of the right diagonals (for blue).
 There is a direct correspondence between the "edge sums" of the square grid and the "diagonal sums" of the quad grid. This is illustrated in the example in the upperleft of the grids.
 The puzzle symbols at the top of each square align with the numbers along the edge of the containing square.
 Indexing into the corresponding puzzle answers with those numbers reads the answer "SECONDPERSONSINGULAR".
 Intepret that as "SECONDPERSON SINGULAR" to get the answer "YOU".
Dan Notes:
This puzzle was also made using the laser cutter. The designs were printed on label stock, stuck to cardboard, covered with a sheet of low tack transfer tape, aligned carefully in the laser cutter's bed (using a jig we manufactured for the purpose), cut, and peeled. The low tack tape was there to prevent the labels from getting scorched and discolored by the smoke from the laser cutting. This took rather a while to make but it sure beat cutting them out by hand.