The Gray Code Decoder and Gray Code Encoder holes will go live in approximately 24 hours. Why not try and solve them ahead of time?
Roman to Arabic in all languages in chars. Achievements Cheevos Holes Languages Medals Miscellaneous All Holes 12 Days of Christmas 24 Game 99 Bottles of Beer Abundant Numbers Abundant Numbers (Long) Arabic to Roman Arithmetic Numbers Arrows Ascending Primes ASCII Table Billiards brainfuck Calendar Card Number Validation Catalan Numbers Catalan’s Constant Christmas Trees Collatz Continued Fractions CSS Colors Cubes Day of Week DFA Simulator Diamonds Divisors Emirp Numbers Emirp Numbers (Long) Emojify Evil Numbers Evil Numbers (Long) Factorial Factorisation Farey Sequence Fibonacci Fizz Buzz Foo Fizz Buzz Bar Forsyth–Edwards Notation Fractions Game of Life Gijswijt’s Sequence Happy Numbers Happy Numbers (Long) Hexdump Hilbert Curve Intersection Inventory Sequence ISBN Jacobi Symbol Kaprekar Numbers Kolakoski Constant Kolakoski Sequence Leap Years Levenshtein Distance Leyland Numbers ln 2 Look and Say Lucky Numbers Lucky Tickets Mahjong Mandelbrot Maze Medal Tally Minesweeper Morse Decoder Morse Encoder Multitap Input Musical Chords N Queens Niven Numbers Niven Numbers (Long) Number Spiral Odious Numbers Odious Numbers (Long) Ordinal Numbers PalindromemordnilaP Pangram Grep Partition Numbers Pascal’s Triangle Pernicious Numbers Pernicious Numbers (Long) Poker Polyominoes Prime Numbers Prime Numbers (Long) Proximity Grid QR Decoder Quine Recamán Repeating Decimals Reverse Polish Notation Reversi Rijndael S-box Rock-paper-scissors-Spock-lizard Roman to Arabic ROT13 Rule 110 Scrambled Sort Set Seven Segment SI Units Sierpiński Triangle Smith Numbers Spelling Numbers Star Wars GPT Star Wars Opening Crawl Sudoku Sudoku (Fill-in) Ten-pin Bowling Tic-tac-toe Time Distance Tongue-twisters Topological Sort Tower of Hanoi Transpose Sentence Trinomial Triangle United States Vampire Numbers Van Eck Sequence Zeckendorf Representation Zodiac Signs γ λ π τ φ √2 𝑒 Alphabetic Numbers Apéry’s Constant Binary Lambda Calculus Connect Four Crossword CSS Colors (Inverse) CSS Grid Ellipse Perimeters Flags Floyd-Steinberg Dithering Gray Code Decoder Gray Code Encoder Hexagonal Spiral Highly Composite Numbers NFA Simulator Numbrix Odd Polyomino Tiling p-adic Expansion Polygon Triangulations QR Encoder Quadratic Formula Rectangle Fill Semiprime Numbers Smooth Numbers Snake Sphenic Numbers Taxicab Numbers Turtle Tutorial All Languages ><> ALGOL 68 ArkScript Assembly AWK Bash BASIC Berry brainfuck C C# C++ Civet Clojure COBOL Coconut Common Lisp Crystal D Dart Elixir Erlang F# Factor Forth Fortran Gleam Go GolfScript Groovy Haskell Hexagony J Janet Java JavaScript jq Julia K Kotlin Lua Nim OCaml Pascal Perl PHP PowerShell Prolog Python R Raku Rockstar Ruby Rust Scheme sed SQL Swift Tcl TeX V VimL Wren Zig 05AB1E APL Arturo Befunge BQN CJam CoffeeScript Egel Fennel Harbour Hare Haxe Hush Hy iogii Knight Lily Luau Odin Picat Qore Racket Rebol Rexx Scala Squirrel Stax Uiua Umka Vala Vyxal Bytes Chars Scoring Bytes Chars Language All ><> ALGOL 68 ArkScript Assembly AWK Bash BASIC Berry brainfuck C C# C++ Civet Clojure COBOL Coconut Common Lisp Crystal D Dart Elixir Erlang F# Factor Forth Fortran Gleam Go GolfScript Groovy Haskell Hexagony J Janet Java JavaScript jq Julia K Kotlin Lua Nim OCaml Pascal Perl PHP PowerShell Prolog Python R Raku Rockstar Ruby Rust Scheme sed SQL Swift Tcl TeX V VimL Wren Zig Experimental Language 05AB1E APL Arturo Befunge BQN CJam CoffeeScript Egel Fennel Harbour Hare Haxe Hush Hy iogii Knight Lily Luau Odin Picat Qore Racket Rebol Rexx Scala Squirrel Stax Uiua Umka Vala Vyxal Hole All 12 Days of Christmas 24 Game 99 Bottles of Beer Abundant Numbers Abundant Numbers (Long) Arabic to Roman Arithmetic Numbers Arrows Ascending Primes ASCII Table Billiards brainfuck Calendar Card Number Validation Catalan Numbers Catalan’s Constant Christmas Trees Collatz Continued Fractions CSS Colors Cubes Day of Week DFA Simulator Diamonds Divisors Emirp Numbers Emirp Numbers (Long) Emojify Evil Numbers Evil Numbers (Long) Factorial Factorisation Farey Sequence Fibonacci Fizz Buzz Foo Fizz Buzz Bar Forsyth–Edwards Notation Fractions Game of Life Gijswijt’s Sequence Happy Numbers Happy Numbers (Long) Hexdump Hilbert Curve Intersection Inventory Sequence ISBN Jacobi Symbol Kaprekar Numbers Kolakoski Constant Kolakoski Sequence Leap Years Levenshtein Distance Leyland Numbers ln 2 Look and Say Lucky Numbers Lucky Tickets Mahjong Mandelbrot Maze Medal Tally Minesweeper Morse Decoder Morse Encoder Multitap Input Musical Chords N Queens Niven Numbers Niven Numbers (Long) Number Spiral Odious Numbers Odious Numbers (Long) Ordinal Numbers PalindromemordnilaP Pangram Grep Partition Numbers Pascal’s Triangle Pernicious Numbers Pernicious Numbers (Long) Poker Polyominoes Prime Numbers Prime Numbers (Long) Proximity Grid QR Decoder Quine Recamán Repeating Decimals Reverse Polish Notation Reversi Rijndael S-box Rock-paper-scissors-Spock-lizard Roman to Arabic ROT13 Rule 110 Scrambled Sort Set Seven Segment SI Units Sierpiński Triangle Smith Numbers Spelling Numbers Star Wars GPT Star Wars Opening Crawl Sudoku Sudoku (Fill-in) Ten-pin Bowling Tic-tac-toe Time Distance Tongue-twisters Topological Sort Tower of Hanoi Transpose Sentence Trinomial Triangle United States Vampire Numbers Van Eck Sequence Zeckendorf Representation Zodiac Signs γ λ π τ φ √2 𝑒 Experimental Hole Alphabetic Numbers Apéry’s Constant Binary Lambda Calculus Connect Four Crossword CSS Colors (Inverse) CSS Grid Ellipse Perimeters Flags Floyd-Steinberg Dithering Gray Code Decoder Gray Code Encoder Hexagonal Spiral Highly Composite Numbers NFA Simulator Numbrix Odd Polyomino Tiling p-adic Expansion Polygon Triangulations QR Encoder Quadratic Formula Rectangle Fill Semiprime Numbers Smooth Numbers Snake Sphenic Numbers Taxicab Numbers Turtle Tutorial # Golfer Points Chars Time Submitted 801st JRaspass 🇬🇧 577 132 10ms 1 Oct 2022 802nd madex 🇩🇪 576 160 190ms 16 days ago 803rd PaulTaykalo 576 170 120ms 24 Sep 2020 804th annaproxy 575 125 20ms 9 May 2022 804th commandz0 🇺🇸 575 125 21ms 21 May 2023 804th davecame 575 125 23ms 14 Sep 2023 807th madex 🇩🇪 575 142 3ms 16 days ago 808th frankgraziano 575 173 22ms 24 Feb 2026 809th CaedenHarper 🇨🇦 574 136 8ms 22 Aug 2025 810th CaedenHarper 🇨🇦 573 124 3,551ms 18 Aug 2025 811th alexsave 573 132 21ms 14 Jan 2026 812th DanielRHolland 573 194 359ms 12 Nov 2020 813th MeWhenI 🇻🇦 572 77 6ms 16 Apr 2023 813th janbehrens 🇩🇪 572 77 6ms 18 May 2023 815th Indivicivet 571 126 20ms 26 Oct 2021 815th vishwathg 571 126 26ms 2 Feb 2023 817th DaCuteRaccoon 569 133 14ms 8 Dec 2022 818th Yewzir 🇧🇪 569 139 143ms 9 Jun 2024 819th MeWhenI 🇻🇦 569 168 1,438ms 16 Jun 2023 820th commandz0 🇺🇸 567 114 537ms 1 Sep 2025 821st CaedenHarper 🇨🇦 567 144 4ms 16 Nov 2025 822nd marcin7Cd 566 127 20ms 28 Sep 2019 823rd Sciman101 566 158 6ms 16 May 2023 824th CaedenHarper 🇨🇦 566 173 757ms 22 Aug 2025 825th annaproxy 564 197 327ms 23 Feb 2023 826th Natanaelel 🇸🇪 563 145 4ms 16 Feb 2026 827th daedals 562 128 19ms 31 May 2019 827th mathb0y512 562 128 21ms 11 Jan 2024 827th mathisfun271 562 128 44ms 13 Feb 2024 827th moustave 562 128 19ms 7 Apr 2025 831st janbehrens 🇩🇪 561 105 2,700ms 18 May 2023 832nd melven 561 215 42ms 16 Oct 2025 833rd GrayJoKing 🇦🇺 560 61 41ms 23 Oct 2020 834th HumanoidCPU 560 135 16ms 8 Jun 2024 835th Jacob385 558 181 388ms 28 Oct 2025 836th CaedenHarper 🇨🇦 557 117 164ms 17 Aug 2025 837th jared-hughes 557 129 21ms 2 Oct 2021 837th ahmetdemirag 🇨🇾 557 129 21ms 4 Jul 2024 839th BambooleanLogic 🇸🇪 556 136 18ms 3 Nov 2022 840th djeedjay 🇳🇱 555 147 3ms 6 Sep 2021 841st CaedenHarper 🇨🇦 555 181 68ms 16 Nov 2025 842nd JunkIce 553 117 462ms 3 Dec 2024 843rd Bmrl7 553 130 21ms 7 Mar 2024 844th emgordon154 552 221 110ms 10 Jun 2025 845th lynn 551 62 42ms 24 Oct 2021 846th Anonymousellama21 549 131 22ms 16 May 2024 847th uttumuttu 🇫🇮 548 138 20ms 5 Jan 2022 847th KaleChips22 548 138 13ms 3 Aug 2025 849th joll05 🇸🇪 545 132 22ms 20 Aug 2020 849th SnowballSH 545 132 28ms 3 Feb 2021 849th jeff-at-tamer-dot-codes 🇺🇸 545 132 23ms 25 Mar 2024 852nd ShiraJoseph 🇺🇸 544 139 21ms 25 Jun 2023 853rd kkoenig 544 228 317ms 13 Sep 2024 854th UnderKoen 🇳🇱 542 225 129ms 8 Jul 2024 855th tkwa 541 133 21ms 4 Dec 2018 855th fourth-bit 541 133 42ms 13 Jul 2023 857th mckymsh 540 140 15ms 1 Mar 2022 858th relet 537 134 21ms 8 Aug 2018 859th phdphil 536 93 232ms 22 Apr 2018 860th bstrautin 535 109 3,906ms 26 Jul 2020 861st jared-hughes 533 64 43ms 17 Apr 2022 862nd suwat513 533 135 43ms 15 Sep 2022 863rd kevinmchung 529 136 28ms 3 Apr 2018 863rd jarekwg 529 136 19ms 2 Oct 2020 863rd OCNeve 529 136 20ms 18 Jun 2024 863rd minhtrancccp 529 136 21ms 25 Nov 2024 867th xkacer 🇨🇿 529 143 18ms 25 Jan 2021 867th trinityy-7 529 143 15ms 17 Mar 2024 869th elgan65536 🇺🇸 529 214 196ms 27 Mar 2024 870th neihousaigaai 525 137 21ms 6 Oct 2024 871st emgordon154 525 144 19ms 9 Dec 2021 872nd adamnielson42 🇺🇸 522 77 36ms 7 Dec 2023 873rd hiddicop 🇸🇪 522 92 55ms 1 Feb 2021 873rd jared-hughes 522 92 47ms 20 Sep 2022 875th Kibble 522 145 13ms 4 Oct 2020 875th IchBinMichMarkus 522 145 15ms 11 Jul 2023 877th CaedenHarper 🇨🇦 522 373 1,517ms 22 Aug 2025 878th IISResetMe 521 112 788ms 8 Mar 2024 878th CaedenHarper 🇨🇦 521 112 329ms 22 Aug 2025 880th zbreit 🇺🇸 521 138 24ms 6 Aug 2020 First Prev 801–880 of 1,509 Next Last