The Calendar hole will go live in approximately 13 days. Why not try and solve it ahead of time?
ISBN in all languages in bytes. 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 Card Number Validation Catalan Numbers Catalan’s Constant Christmas Trees Collatz 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 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 Apéry’s Constant Binary Lambda Calculus Calendar Connect Four Continued Fractions Crossword CSS Colors (Inverse) CSS Grid Ellipse Perimeters Flags Floyd-Steinberg Dithering Gray Code Decoder Gray Code Encoder Hexagonal Spiral Highly Composite Numbers Multitap Input NFA Simulator Numbrix Odd Polyomino Tiling p-adic Expansion Polygon Triangulations QR Encoder Quadratic Formula Semiprime Numbers Smooth Numbers Snake Sphenic Numbers Taxicab Numbers Turtle Tutorial All Languages ><> 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 ALGOL 68 APL Arturo Befunge BQN CJam CoffeeScript Egel Fennel Harbour Hare Haxe Hush Hy iogii Knight Luau Odin Picat Qore Racket Rebol Rexx Scala Squirrel Stax Uiua Umka Vala Vyxal Bytes Chars Scoring Bytes Chars Language All ><> 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 ALGOL 68 APL Arturo Befunge BQN CJam CoffeeScript Egel Fennel Harbour Hare Haxe Hush Hy iogii Knight 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 Card Number Validation Catalan Numbers Catalan’s Constant Christmas Trees Collatz 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 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 Apéry’s Constant Binary Lambda Calculus Calendar Connect Four Continued Fractions Crossword CSS Colors (Inverse) CSS Grid Ellipse Perimeters Flags Floyd-Steinberg Dithering Gray Code Decoder Gray Code Encoder Hexagonal Spiral Highly Composite Numbers Multitap Input NFA Simulator Numbrix Odd Polyomino Tiling p-adic Expansion Polygon Triangulations QR Encoder Quadratic Formula Semiprime Numbers Smooth Numbers Snake Sphenic Numbers Taxicab Numbers Turtle Tutorial # Golfer Points Bytes Time Submitted 637th davitf 781 113 9ms 30 Apr 2024 637th kbeat 🇰🇿 781 113 12ms 18 May 2025 643rd AlephSquirrel 781 130 6ms 21 Oct 2024 644th LHLaurini 🇧🇷 781 141 59ms 17 Jul 2024 645th adamnielson42 🇺🇸 780 91 9ms 26 Apr 2023 645th luuumine 🇫🇷 780 91 9ms 12 Nov 2025 647th Shanethegamer 🇺🇸 780 104 72ms 4 Dec 2024 648th Shanethegamer 🇺🇸 780 161 41ms 13 Feb 2025 649th MeWhenI 🇻🇦 779 43 4ms 1 Mar 2025 650th MeWhenI 🇻🇦 779 96 135ms 25 Oct 2024 651st fuzzylojik-golf 🇺🇸 779 98 406ms 6 Jul 2025 652nd retrohun 778 121 2ms 30 Dec 2022 652nd abc7-12 778 121 1ms 26 Jun 2024 654th Yewzir 🇧🇪 778 135 7ms 16 Dec 2023 654th Maximizer02 778 135 8ms 24 Sep 2024 656th JRaspass 🇬🇧 776 60 3ms 18 Jan 2023 657th call23re 776 112 2ms 12 Jan 2022 658th kmathis22 776 138 444ms 30 Oct 2025 659th rak1507 🇬🇧 775 40 2ms 10 Jan 2022 659th Frowny 775 40 2ms 13 Jan 2022 659th jared-hughes 775 40 55ms 29 Jul 2022 659th razetime 775 40 3ms 22 Aug 2022 663rd Shanethegamer 🇺🇸 775 76 449ms 12 Oct 2022 663rd stefangimmillaro 775 76 998ms 8 Jan 2023 663rd MeWhenI 🇻🇦 775 76 997ms 10 May 2023 663rd error256 775 76 1,078ms 14 Feb 2025 667th primo-ppcg 🇹🇭 775 118 337ms 9 Apr 2022 668th primo-ppcg 🇹🇭 775 131 6ms 20 Jan 2023 669th Steffan153 🇫🇮 775 132 13ms 5 Jul 2024 670th DialFrost 🇸🇬 775 142 2ms 14 Sep 2024 671st andersk 🇺🇸 775 156 236ms 30 Oct 2022 671st emgordon154 775 156 243ms 14 Mar 2025 673rd aonkeeper4 774 114 9ms 5 Jul 2022 673rd frankgraziano 774 114 10ms 8 Jan 2023 673rd m42km 774 114 9ms 22 Nov 2023 673rd thienudomsrirungruang 774 114 16ms 14 May 2024 673rd jtaxen 774 114 10ms 8 Jun 2024 673rd CutSandstone 774 114 9ms 8 Jul 2024 679th strout 774 145 148ms 15 Aug 2022 680th juliansiebert 🇩🇪 773 72 274ms 24 Jul 2022 681st maxpelic 🇺🇸 772 92 9ms 5 Jul 2022 681st astdefu 772 92 9ms 10 Dec 2022 681st two-bad 🇬🇧 772 92 9ms 25 Feb 2024 681st KatieLG 🇬🇧 772 92 9ms 8 Jul 2024 685th Steffan153 🇫🇮 772 106 79ms 21 Jun 2024 686th c0d3-4-F00d 🇩🇪 772 122 2ms 21 Feb 2022 687th emplv 🇱🇻 771 101 100ms 6 Dec 2022 688th Yewzir 🇧🇪 770 115 139ms 26 Dec 2023 689th Shanethegamer 🇺🇸 770 157 149ms 8 Oct 2022 690th primo-ppcg 🇹🇭 768 67 20ms 24 Jan 2022 691st Shanethegamer 🇺🇸 768 99 90ms 12 Dec 2022 692nd jmerle 🇳🇱 768 115 9ms 22 Jan 2022 692nd PiterAnnema 768 115 16ms 23 Mar 2022 692nd AGoyet 768 115 9ms 29 Jun 2022 692nd Eilonlif 🇮🇱 768 115 10ms 11 Sep 2022 692nd IsmaelGSerrano 768 115 10ms 2 Nov 2022 692nd bobbysq 768 115 9ms 22 Jan 2023 692nd msbranicky 768 115 9ms 25 Jul 2023 692nd ArenaGrenade 768 115 10ms 19 Feb 2024 692nd NickTheEASDude 🇺🇸 768 115 10ms 15 May 2024 692nd dokutan 768 115 10ms 13 Aug 2024 692nd maxgodfrey2004 🇨🇦 768 115 10ms 8 Jan 2025 692nd Pyroan 768 115 9ms 21 Feb 2025 692nd chartung17 768 115 10ms 24 Mar 2025 705th CatsAreFluffy 766 57 50ms 9 Jan 2023 705th xsot 🇸🇬 766 57 52ms 2 Feb 2024 707th iczelia 🇩🇪 766 123 1ms 24 Sep 2025 708th DialFrost 🇸🇬 765 71 42ms 26 Dec 2024 709th MeWhenI 🇻🇦 765 81 699ms 15 Sep 2025 710th edsrzf 🇳🇿 765 107 73ms 28 Jun 2025 711th GrayJoKing 🇦🇺 765 126 421ms 1 Mar 2022 712th Andrey-Plotnikov 764 93 9ms 21 Jun 2025 712th Protothor 764 93 9ms 9 Jul 2025 714th DialFrost 🇸🇬 764 133 6ms 11 Dec 2024 715th jerrandolph 764 174 251ms 20 Oct 2023 716th stefangimmillaro 763 102 99ms 19 Oct 2022 717th annaproxy 763 134 13ms 24 Dec 2022 718th kejcao 🇨🇦 763 147 193ms 3 Aug 2024 719th Shanethegamer 🇺🇸 762 73 264ms 14 Jun 2024 720th DialFrost 🇸🇬 762 114 2ms 1 Nov 2024 First Prev 641–720 of 1,566 Next Last