Here's a basic chart showing what's where in this long list of problems. There are two fully detailed lists in the User Guide:  SDS Topics in Alphabetical Order and SDS Topics in Numerical Order.

TopicStella Number
Visual Problems1000 – 1170
Logical Deduction1180 – 1290, 3750
Arithmetic1300 – 2022
Symbol Manipulation2030 – 2390, 2745, 4100
Algebra Problems2400 – 2500
Analytic Geometry2750 – 2840, 3680 – 3723
Informal Geometry3000 – 3080
Euclidean Geometry3100 – 3650, 3750 – 3850
Trigonometry4000 – 4340
Probability4400 – 4420

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Stella NumberProblem Title
1000.11Three Shapes, Three Numbers
1000.12Looping Paths
1000.15Telling Time Backwards, Part I
1000.16Telling Time Backwards, Part II
1000.21Floor Tile Reflection no. 1
1000.22Floor Tile Reflection no. 2
1000.23Floor Tile Reflection no. 3
1000.26Nasty Page Fold
1000.31Tents Among Four Trees
1000.41Non-Intersecting Paths on Grid
1000.45Line Fragments no. 1
1000.46Line Fragments no. 2
1000.47Line Fragments no. 3
1000.53Stella's Fishpond
1000.54Swapping Places
1000.55Novice Bagpipers
1000.56Yearbooks Meet Bookworm
1000.57A Line of Men
1000.61Poison Pills
1000.65An Alphabet Line
1000.66Alphabet Line
1000.72Clock Hands, Purple Flashes
1000.75Scott the Painter
1000.81Continue the Pattern
1000.82Acropolis Pattern
1000.91Chessboard Dominoes
1000.92Students Change Seats
1000.93The Eight Queens Puzzle
1000.94Take a Walk on a Checkerboard
1007.11The Impossible Path
1007.21Trace This Network
1007.22Continuous Line Drawing
1009.11Triangle Count
1009.21Squares on a Checkerboard
1009.31Counting Squares
1009.41Squares on a Lattice
1010.11Squares in a Square
1010.41Sequences of Squares
1010.42More Sequences of Squares
1020.12Covered Shapes
1020.15A Triangle with Given Midpoints
1020.23Vacation on a Triangular Island
1020.42Overlapping Squares
1020.44Dividing the Yin and the Yang
1020.51Manhole Covers
1020.71Cutting a Sheet Cake
1027.11Partition This Shape no. 1
1027.12Partition This Shape no. 2
1027.13Partition This Shape no. 3
1027.14Partition This Shape no. 4
1027.15Partition This Shape no. 5
1027.23Partition This Shape no. 13
1027.24Partition This Shape no. 14
1027.25Partition This Shape no. 15
1027.26Partition This Shape no. 16
1027.27Partition This Shape no. 17
1027.28Partition This Shape no. 18
1027.31Partition This Shape no. 21
1027.32Partition This Shape no. 22
1027.33Partition This Shape no. 23
1027.42Siamese Fighting Fish
1027.44Congruent Gardens
1030.11Nine Dots
1030.12Sixteen Dots
1030.21Utility Lines
1040.11Ten Peach Trees
1040.21The Wigglesworth Apple Trees
1040.31Moving a Circle
1050.11Penny Triangle
1050.61The Rolling Penny
1060.11Disappearing Toothpick Squares
1060.21Toothpick Triangles
1060.41Moving Toothpicks
1070.12This Man's Father
1070.13The Snail in the Well
1070.14Beetle and Rock
1070.15Pirate Queen Harriet
1070.16Woodie Lott
1070.19Watson's Purchase
1070.21Grandfather Clock Strikes
1070.23State a Theorem
1070.31You'll Never Guess
1070.33Snails and Details
1070.43Park Run
1079.12Weedsport Clothing Boutique
1079.41Word Triangle Arithmetic
1090.21Labeled Cube Views
1090.22Cube Frames
1090.24Looped Rings
1090.25Bohemian Chain Mail
1090.26Equitable Cake Cutting
1090.31Mixed Sticks
1090.33Cube Patterns
1090.35Cube View 2
1090.36Cube View 3
1090.37Cube Identification
1090.41Cutting a Rectangle
1090.42Six Toothpicks
1090.51Stark, Raving Bonkers
1090.53Two Views, One Object
1090.61A Pile of Cubes
1090.71Twenty-Seven Little Cubes
1090.72Cube, Orange, Made and Unmade
1090.73Cutting a White Pine
1090.74How Big is This Cube?
1090.75Fly on the Cube
1090.91The Pierced Cube
1090.93The Six-Cubed Thing
1090.94The L-shaped Block
1095.11What Lies Opposite?
1095.12The Checker-Boarded Face
1100.11The Old Wooden Disc
1100.22Continue a Numerical Pattern
1100.51Agatha the Cow
1100.52The Flu
1100.71Martha the Grocer and her Two-Pan Scale
1110.11Numbers in Circles
1110.22Around the Corners
1110.41Digit Cells
1110.43A Fancy 8-Digit Number
1110.44Ten Billiard Balls
1110.61Security Guards
1120.11Crossnumber Puzzle no. 1
1130.11A Magic Square with Primes
1140.11Two Pails and a Duck
1140.14Sharing Soda
1140.51A Phone Call
1160.12ALAS LASS part 2
1160.31Product Places
1160.32Multiplication Puzzle
1170.21Money Bag
1170.23Yearbook Earnings
1170.24Dimes and Pennies
1170.42Can't Change a Dollar Bill
1170.91Path of Quarters
1170.92A Ton of Pennies
1170.93The Weight of 1000 Dollars in Dimes
1170.94Total Tree Growth
1180.21Missing Dollar
1180.22Horse Trading
1180.23Tony's Hat
1180.32Commute to Possum City
1180.35Flutists and Violinists
1180.36Restaurant Staff Puzzle
1180.37Dogs, Cats, Snakes
1180.41Sherman and Cyrus
1180.42Chain Links
1180.43Gleepers & Blahmies
1180.44Social Scale of Boojums
1180.45Biology Lesson
1180.46Bike to the Beach
1180.61Mathies and Websters
1180.62Robins Here and There
1180.64Paper Thickness
1180.65Tennis Tournament
1180.66The Problem Before . . .
1180.81Horse Race
1180.83Vanilla Yoghurt
1180.84Mixing Wine and Water
1190.11Charlize's Age
1190.12Light Year
1190.14Running for President
1190.17Digital Clock Minutes
1190.18Breaths in a Year
1190.19Two Erratic Clocks
1190.31Charlie and LaQuanda
1190.32The Phone Booth
1190.34Kant's Clock
1190.52Day Before Yesterday
1190.53No Weather
1192.21Anastasia's Birthday
1200.11Contest Results
1210.21Cheerleader Tryout
1210.31Pigeon Island
1220.11Five Houses, a Camel, and Lemonade
1230.11Baseballs and Grapefruit
1230.21The Gardner, the Baker, and the Fisher
1230.22Train Crew
1230.32Blue, White, and Gray
1230.33Four Athletes
1230.34Super-Duper Market
1230.36Tennis-Playing Family
1230.41Hot Potato
1230.42Who is Going with Whom?
1230.43Student Body Officers
1230.44Glenda Aces a Quiz
1230.46Tina's Trip
1230.47Ant, Bat, Cat
1230.51Playing Cards to Identify
1230.52Spirit Week Bake Sale Booth
1230.53Who is in Which Family?
1230.54Students and Cars
1230.55Letters and Envelopes
1230.56Take your Pills
1230.61Amy, Brenda, Christa, Dana
1230.63Maurice’s Video Games
1230.64Card Nonsense
1230.65Identify the card
1230.71Chemical Conundrum
1232.11Soccer Scores
1232.31Six Who Witnessed a Burglary
1240.11A Fox, a Goose, and a Bag of Corn
1240.12Four Men, Two Boys, and a Boat
1250.11False Coin no. 1
1250.12False Coin no. 2
1250.13False Coins no. 3
1260.01Handshakes (24, 1)
1260.02Handshakes (n)
1260.21Handshakes; Fly on the Wall
1270.12Pigeonholes no. 2
1270.13Globs and Glitches
1280.11Toad Tales
1280.12Highland Island
1280.21Spying on Student Council
1290.11Ice Cream Survey
1290.13A Hot Air Balloon Club
1290.14Gym Class
1290.15CSD student body
1300.11Mystery Number
1307.11Consecutive Integers Sum
1307.12Four Consecutive Integers
1307.31Consecutive Integers, Sum of 100
1310.11Evens Minus Odds
1310.25Super Venn Diagram
1310.31Resupplying the International Space Station
1310.41Dartboard with a Black Hole
1310.61Never 100
1320.11The Number of Digits in a Product
1322.11Giant Powers of 3
1322.14Chinese Remainders
1330.11Square Mistake!
1331.11Guess My Age!
1331.12Louie's Age
1331.14Difference of Squares
1332.11Whole Number Radicals
1334.11Square and Cube
1340.52Pocket Change
1365.11Decimals On Screen
1368.21Torture with Fractions
1368.25Egyptian Fractions Intro
1368.31What's That Fraction?
1370.11Gain Versus Loss
1370.21Dust Mites
1380.11Some Sums
1380.31Find the falsehood
1395.21Radical in Radical
1410.11How Many Digits?
1410.12A Number Pattern
1430.11The Mean 9's
1460.21Target Products
1470.12Tearing and Stacking
1470.41A Giant Sum
1470.51Heartbeats per Month
1470.52Heart Beats
1470.53Dripping Faucet
1470.54A Million Drops of Water
1480.11Repeating Digits in Addition
1480.21A Large Multiple of 17
1480.41Broken $\surd$ Key
1490.12The Number One First Class Happy Bank
1490.16Buying Sand
1490.21Prom Bands
1490.31Tie-Dyed T-Shirts
1510.11Heap: An Egyptian Equation
1510.21Pamela Gore
1510.22Pebble's Long Life
1510.41Alex Watt's Will
1510.42Farmer Fox
1510.43Ftatateeta's Scarabs
1510.51Stella's Musical Scores
1510.52Totem Pole
1530.21Choir Risers
1530.32Basil's Age
1530.33I Have a Good Friend in Maumee
1530.34Paul's Cheese
1530.35Mr. Eby's Spare Tire
1530.36Lake Erie
1540.21Golden Oldies
1540.33Hattie's Age in 1900
1540.34Aggie's Eggs
1540.35Apples on a Hike
1540.36Conquest of Bread
1540.37Celeste in Obieland
1540.41Brine Tank
1540.51Electric Bill Printing
1540.61Tape Sale
1540.71Stella's Barbecue
1540.72Waterbed Weight
1550.11Shelley, Veronica, Christy, and Ruth
1550.12Malaz, Ron, Debra, and Sabrina
1550.14Toy Rocket
1550.15Rooster, Goose, Duck Prices
1550.16Harnessing Horses
1550.18Jacob's Bumper
1550.19Wrestlers on the Scale
1550.21Speeding Cycles
1550.22In A Dream
1550.23Batting Average no. 1
1550.24Sibyl Bibble
1550.25Tree and Nests
1550.26Brick on a 2-Pan Scale
1550.27Mr. Adams's Will
1550.28Swerve's Bikes and Skateboards
1550.29Restaurant Bill
1550.31Rick's Bed
1550.32Eggs to Carry
1550.33Basketball Game Tickets
1550.36Splitting up Eighty-Eight
1550.38Bananas and Pears
1550.39Trading Cards
1550.41Cows and Oxen
1550.42Pythagoras Party
1550.43A Horse and a Mule Converse
1560.11Picka Numba
1560.12Leon Cranville's Picka Numba
1600.13A Prime Number
1600.21Even Numbers and Primes
1600.31Getting to Fort Wayne
1600.41Primes Conjecture
1610.11One Million
1610.12Primes in Product
1610.31Nasty Numbers
1640.31Ballpoint Pen Sale
1640.41Find the Number!
1640.61The Largest What! The Smallest What!
1650.12Jasper's Marbles
1650.13Wok Around the Clock
1650.21Dorothy and the Eggs
1650.31Divisibility Theorem (Sum)
1680.11Factorial Perfect Squares?
1720.41Patterned Equations
1720.51Maximum Product
1730.31Counter-Factual Theory
1730.32Squares and Cubes in a Pattern
1730.41Need More Money?
2020.11Expand That Binomial!
2050.21Four Fours: One to Twenty
2050.22Four 4’s: 21 – 40
2050.41Six Nine's Make A Hundred
2050.44Parentheses Insert
2070.12Formula for Apple Fritters
2070.13The Price of a Dozen Kumquats
2070.14Ghanaian Shirts
2070.21Mrs. McGillicuddy's Age
2070.22Alyssa's Formula
2070.23Babysitting Rates
2070.33A Rectangular Box
2070.41Stacking Grapefruit
2070.43Big and Little Cubes
2070.51Square of Dates
2070.61Big Round Dinosaur Buttons
2070.71Next Perfect Square
2070.82Mystery Function
2070.83Bowling Uphill
2070.84Particle Motion
2100.12Who's The Champion?
2100.21Symmetric Exponents
2100.32Sums of Odd Numbers
2100.33Sum of Odd Numbers
2100.35Fiddling with Exponents
2100.52Rational Expressions, Laws of Exponents
2100.81A Product Plus One
2110.11Big Product
2110.12Giant Distribution
2110.34Three Numbers
2120.11Messy Numerical Expression
2121.11Unlikely bandanas
2122.11Factoring a Cubic
2122.14Divisibility by 16
2122.15Pairs of Integers
2122.41Perfect Square?
2140.11Triple Ratio
2140.31Gear Wheels
2140.71Beakers, Ratio of Acid to Water
2150.11Difference of Reciprocals
2150.21Reciprocal Symmetry
2150.22Diminished by a Reciprocal
2150.41Adding x to Numerator and Denominator
2150.62Lowest Terms?
2150.72Find the Equivalent
2150.81A Horrendous Quantity
2152.22Catch a Robber and Maximize Your Reward
2162.11An Infinite Continued Fraction
2180.11Real-valued Radical
2200.11Positive Integer Solutions: Count Them
2200.21An Equation with Fractions
2200.61Holstein or Guernsey?
2210.11Fraction Inequality
2210.32Fractional Inequality
2210.41Distance on the Number Line
2210.71Point on a Line. Making a Triangle?
2210.81An Inequality with Radicals
2211.11Absolutely Unequal
2211.21Product with an Absolute Value
2220.11Timbuktu Post Office
2230.11DON'T GUESS!
2230.22The Golden Ratio
2230.31A Circle and a Parabola
2230.32A Quadratic Question
2230.41Find the Smallest Root
2230.51Jessamine Bush
2230.62Two Quadratics
2230.63Almost Equal Roots
2230.81Cathy the Cat Burglar
2232.11From a Progression to a Quadratic
2240.11A Butterfly Garden
2250.11A Nice Rational Equation
2250.21Strange Equation
2260.11Huge Difference of Squares
2260.21A Fourth Degree Equation
2260.31Outrageous Cube Root
2260.41Two Cubes
2288.11A Symmetric Equation
2290.11The Dutch Miller
2290.41Wine and Punch Bowls
2300.11Exponential Equation With Threes
2310.11Fleet Street Market
2310.21Coffee Break
2310.31Intersecting Lines
2315.11Equations with No Solution
2405.12Pickanumba 1
2405.24Translation into Algebra
2410.11A Salesman's Commission
2410.12Spend or Save?
2410.13Bertha's Tax
2410.21Tennis Team
2410.23Igor's Foul Shots
2410.33Battling Percentages
2410.34Wendy the Chemist
2410.42Pompeii Geothermal Corp. Wages
2420.11Hen and a Half
2420.12Hen and a Half, Variables
2420.21Horses and Oats
2420.31Watering Your Venus Flytrap
2420.34Emptying the Swimming Pool
2420.35Robots at Work
2420.41The Cow, the Goat, and the Wildebeest
2420.51Glenice Burns her Candles
2420.62Brick Wall
2430.11Three Valves
2440.11Beef's Lost Loot
2440.13Driving to Nirvana
2440.14Trains DC-NYC
2440.15Rocket Sled
2440.17Maggie and Aggie
2440.21Duckburg to Possumtown
2440.31Columbus to Cincinnati
2440.32Driving to Atlanta
2440.33Susu the Cat
2440.41York to London
2440.51Race to the Bus
2440.52Wilbur's Boat Trip
2440.62Bike Ride to Oberlin
2440.63Rashon and Santiago
2440.70Snow Tires Versus Ordinary Tires
2440.71Uther and Eethyl
2440.74Fly Between Trains
2440.75Around the Reservoir
2440.76Jetta versus Corvette
2440.77Barnabas and the Overpass
2440.78Figure Eight Racing
2440.79There's a Train in that Tunnel
2440.82Gabriela and her Chauffeur
2440.93Train Speed
2442.52Daniel Boone on Plum Creek
2452.12Doctors and Lawyers Play Dodgeball
2452.13Fifty Mycologists
2452.14Math Team Average Weight
2452.31Strange Batting Average
2452.33Batting Average no. 2
2454.11How Mean?
2460.11Angela's Age
2460.13Ezzaldeen's Age
2460.15The Year the Old Cow Died
2460.27Jianyi and Dylan's Ages
2460.28Present and Future Ages II
2460.29Present and Future Ages III
2460.31Present and Future Ages III
2460.81An Unlikely Coincidence
2465.11The Luxury Yacht Gemini
2465.21Stephanie and Bonnie's Ages
2465.31Dorcas Ducat's Age
2465.99The Rope
2470.11Backlot Books
2470.21The Barbell Exchange
2470.31Jellybean Profits
2470.52Teapot Trade
2470.62Solar Panel
2480.11A Birthday Present in Dimes and Quarters
2480.31Dividing A Tenner
2480.51Trading Marbles
2490.11Supermarket Apples
2490.21Kite Strings
2490.32The Grow'm Good Nursery
2500.11Pet Rocks
2500.21Finding Sides of a Triangle
2500.31Foxes and Owls
2500.41Milly and Molly Make Muffins. So Do Their Mothers!
2500.51Defeating, Then Passing a Bill
2500.61Cows, Sheep, Horses
2500.63Kumquat House Numbers
2500.71Airplane Baggage
2500.81Euler Problem: Equal Shares of a Fortune
2510.11Defined Operation no. 1
2510.21Defined Operation no. 2
2510.31The Add-One-Subtract-One Operation
2530.11Defined Operation; Find Formula
2530.31Mystery Linear Operation
2530.41Composition with a Defined Operation
2530.51Defined Operation 3; Do Composition
2530.52Defined Operation 4; Do Composition
2530.73Strange Salary
2544.11Function as Average
2580.11Big f(x), Find f(6)
2580.22If . . . Then . . .
2580.41A Seventh Power Equation
2580.51A Hard Functional Equation
2580.61Sequence Formula
2590.12Function Graphs
2600.12Postage Function, Using [ ]
2615.11A Mystery Function
2660.11Imaginary Roots
2680.11Cubic to Quadratic to Linear
2702.11Add'Em Up
2710.11Sum of Digits
2720.11Minimizing the Sum of Distances
2730.32Nothing but Logs
2730.33Love Those Logarithms
2730.39Complicated Log Equation
2740.11Relating Two Logs
2740.38Find k (logarithms)
2760.21Adjacent Corner of a Square
2761.11A Sum of Slopes
2761.12Collinear Vertices of Squares
2761.13A Tantalizing Trapezoid
2764.11Stella's Fishpond II
2770.21Lines! Intersecting!
2770.31Trisection Points
2770.51Moving Line
2782.11Minding Your p's and q's
2784.11Big Stone Arch
2788.21Circle through (1989,y)
2788.31Two Circles and a Line
2850.41A Recursive Sequence
2850.48Continue the Sequences
2850.49Continue the Sequence
2850.51What's The Next Term?
2850.611, 2, 2, 1, 1, 2, 1, 2, 2 . . .
2850.65A Sequence by Subtraction
2860.11Integer Sum of Unknown Length!
2860.31Even and Odd Numbered Terms
2860.41Fraction Pattern
2860.51Robot Stones
2860.61Arithmetic Sequence I
2870.11Levy's Basketball
2870.21A Mixed Geometric and Arithmetic Sequence
2890.11Fibonacci Numbers Mod 11
3050.11Fireman on the Ladder
3050.12Bugs on a Branch
3060.51Red and Blue Point Line Segment
3060.52Red and Blue Point Triangle
3060.53Red and Blue Point Parallelogram
3060.54Red and Blue Points, Right Angle
3060.55Red and Blue Point Octagon
3060.61People In Groups
3065.11Red/Blue Tubular Neon Lights
3070.11Algebra with Angles
3070.12A Supplement/Complement Conjecture
3080.31Seventeen Opinionated People
3150.11Calculating an Angle
3155.21Jasmine and Biscuit
3155.22A Triangular Garden
3155.41A Mystery Angle
3155.51A Narrow Sinister Alley
3155.61Triangle Cleverness
3160.11Triangle ABC is Isosceles
3261.11Quadrilateral BCDF is a Rhombus
3305.11Diagonals of Two Regular Polygons
3305.51Making a Regular Octagon
3305.52Stop Sign
3310.11Sum of Interior Angles
3310.19A Pentangle
3320.11A Ratio of Areas
3320.21A Square Inside a Circle Inside a Square
3321.11A Circle and A Square
3340.12Trapezoid Angle Measure
3350.11Overlapping Parallelograms
3360.11Mystery Trapezoid
3360.21Rectangle Decomposition
3360.22City Hall Tile Floor
3405.11Seven Rectangles
3405.12Impossible Rectangle?
3405.31Pumpkin Patch
3410.32Squares Make An Octagon
3415.11The Square Community Garden
3420.11Half a Square Foot
3420.12Two Squares
3420.22The Area of a Cross
3420.24Three Equilateral Triangles
3420.25The Sum of Two Triangles
3420.26Area of a Hexagon
3420.27Triangle Area
3420.28Shaded Square Area
3420.29Midline Triangle
3420.31The Trapezoid and the Triangle
3420.41Dance of the Area Bisectors
3420.43Regular Triangle, Regular Hexagon
3420.51Area of a Regular Pentagon
3420.61Two Triangles and a Square
3420.71Hard Triangle Area
3420.73Crazy Baseball Diamond
3420.81Intersecting Medians
3440.12Billy the Goat
3440.13A Girl and Her Dog
3440.31A Lovely Circular Lawn
3440.41First: Trisect the Diameter
3440.43Fencing Inside a Circular Field
3440.51Fraction of a Circular Area
3440.61Design for a Pendant
3440.62Area of an Axe Head
3450.21Tetrahedron Inscribed in a Cube
3460.11Split That Triangle!
3470.12Radio Antenna
3470.14Square with Internal Segments
3470.16Area of a Triangle
3470.21Distance in flight
3470.32Cardboard Box
3470.51A Triangle in a Circle
3470.61Barber Pole
3475.11The Unknown Edge
3500.11Segment in a Circle
3500.21Midpoint of a Chord?
3500.31Circle Around Three Squares
3500.41Water Pipes Stack
3500.51Gertrude the Goldfish
3500.61Three Circular Disks
3500.63Four Tangent Circles
3500.71Find the Radius
3510.11Describe that Shape!
3510.13Is It a Parallelogram?
3520.11The Balancing Pot
3530.11Diameter of a Circle
3550.11LP Phonograph Record
3550.21Clock with Revolutionary Bug
3550.23Our Whirling, Twirling, Swirling World
3550.24Put Your Hands Together
3550.44Walking the Equator
3550.51A Wheel Within A Wheel
3560.11Intersecting Chords
3580.13Two Equilateral Triangles
3580.14Akashi-Kaikyo Bridge
3580.15Estimating Height
3580.17Similarity Exercise
3580.21All Angles
3590.11Parallelogram and a Geometric Mean
3640.11Basketball in a Box
3650.11Peanut Butter Pricing
3650.13A Solid Cube of Bricks?
3650.14Tennis Balls
3650.15Pouring Water
3650.21Two Barrels
3650.23Big Rectangular Solid
3650.31Volume and Surface Area of a Cube
3650.41Pouring Between Glasses
3650.51Box in a Hat
3650.61Triangular Pyramid
3680.21Grasshopper Jump
3680.31Finding a Slope
3695.11A Square in a Cube
3721.11Symmetric Lines
3750.13Wind Farm Fun Facts
3750.21Negating Barbells
3750.31Yobs, Blobs, and Slobs
3750.41Find the Falsehoods
3750.61Pickled Walnuts
3750.72Subsistence Allowance
3750.73Mongoes, Booms, and Flems
3750.74Toxic Tangles
3850.11Rhombi, Locus of Vertex
3850.12The Caged Triangle
3850.14Where Are The Crumbs?
4040.11When Does sin(x) = x/100?
4050.11Angles in a Special Triangle
4050.12Area External to Two Circles
4050.14From Tangent to Sine
4100.11Compound Fraction: Trig
4100.12There's A Cosine In It
4100.21Find a Sine
4100.22Cosine of Three
4100.31Sin(x) + Cos(x)
4100.41That's Impossible!
4120.11Insulating Tape
4120.21The Fibonacci Area Paradox
4140.11Find the Circumference
4200.11Tetrahedron Cutoffs
4200.21A New Volcano
4200.23The Yacht Gemini on the Hudson
4200.24Rocket Launch
4200.25Sighting an Airplane
4200.27The Top of the Turbine
4200.42The Vertical Tower
4220.11View to the Horizon
4220.21Circumnavigating the Earth by Plane
4220.41Stork's Nest
4310.31Star of David
4400.11Knowing the Shot
9999.99Who is in which family?