The Calendar hole will go live in approximately 25 hours. 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 797th Ripick 742 119 10ms 2 Feb 2023 797th Ythaenagor 742 119 10ms 5 Aug 2024 797th PyryL 🇫🇮 742 119 10ms 20 Aug 2024 797th JunkIce 742 119 9ms 25 Nov 2024 797th Stockoh 🇫🇷 742 119 9ms 13 Feb 2025 797th Alban-Boissard 742 119 10ms 14 Jun 2025 797th Flekay 🇩🇪 742 119 9ms 10 Jul 2025 808th BambooleanLogic 🇸🇪 740 96 9ms 20 Aug 2022 808th vroup 🇩🇰 740 96 9ms 2 Oct 2022 808th Ultra814 740 96 9ms 17 Aug 2025 808th tomh1012 740 96 9ms 21 Nov 2025 812th BlankSpruce 739 149 61ms 16 Jan 2022 813th weliveinhell 🇭🇹 739 180 262ms 4 Oct 2023 813th emgordon154 739 180 264ms 20 Feb 2025 815th emplv 🇱🇻 739 182 25ms 31 Oct 2022 816th KenanSi 738 42 2ms 24 Feb 2022 816th Natanaelel 🇸🇪 738 42 2ms 21 Jun 2022 816th GolfingSuccess 🇬🇷 738 42 2ms 31 Dec 2022 819th edsrzf 🇳🇿 738 164 311ms 29 Jul 2025 820th SirBogman 🇺🇸 737 59 34ms 8 Sep 2022 821st billings7 🇬🇧 737 105 353ms 12 Nov 2023 821st MiffOttah 737 105 402ms 28 Nov 2024 823rd fkantelberg 736 120 9ms 18 Jul 2023 823rd Bmrl7 736 120 9ms 29 Feb 2024 823rd elgan65536 736 120 16ms 1 Apr 2024 823rd robin-scragg 736 120 10ms 25 Jul 2025 827th jared-hughes 736 128 2ms 17 Mar 2022 828th JRaspass 🇬🇧 735 181 264ms 23 Sep 2022 829th Waffle3z 734 74 37ms 12 Jan 2022 829th olleicua 🇺🇸 734 74 38ms 16 Feb 2024 829th emgordon154 734 74 42ms 25 Jun 2024 832nd commandblockguy 🇺🇸 734 104 926ms 1 Sep 2025 833rd yzhs 🇩🇪 734 153 146ms 25 Jun 2023 834th SirBogman 🇺🇸 734 320 15ms 21 May 2022 835th dokutan 732 97 9ms 5 Jun 2025 835th iczelia 🇩🇪 732 97 9ms 26 Sep 2025 835th johnkiernander 732 97 9ms 16 days ago 838th Yewzir 🇧🇪 732 137 38ms 28 Nov 2023 839th GolfingSuccess 🇬🇷 731 80 5ms 17 Aug 2024 840th ericlangedijk 🇸🇮 730 106 352ms 19 Mar 2022 841st Natanaelel 🇸🇪 730 121 9ms 12 Jan 2022 841st NerdyMcNerd42 730 121 9ms 20 Aug 2022 841st Kloppermand 🇩🇰 730 121 10ms 3 Oct 2022 841st ehulinsky 🇺🇸 730 121 16ms 15 May 2023 841st AbhilashaTandon 730 121 10ms 21 Sep 2023 841st davecame 730 121 9ms 2 Oct 2023 841st gussy420 730 121 9ms 23 Oct 2023 841st tobyLovick 730 121 9ms 13 Dec 2023 849th retrohun 729 151 64ms 30 Dec 2022 849th annaproxy 729 151 63ms 5 Jan 2023 851st mlugg 728 203 1,617ms 10 Aug 2024 852nd Shanethegamer 🇺🇸 727 138 38ms 6 Sep 2022 853rd MeWhenI 🇻🇦 726 72 2ms 13 Nov 2022 854th krcs 🇵🇱 725 98 9ms 2 May 2022 854th stefangimmillaro 725 98 8ms 12 Sep 2024 856th jared-hughes 724 75 39ms 9 Sep 2022 857th jm600 724 122 9ms 19 Apr 2022 857th krcs 🇵🇱 724 122 10ms 29 Apr 2022 857th bbakersmith 724 122 10ms 6 Jun 2022 857th nstearns96 🇬🇧 724 122 10ms 29 Nov 2022 857th stertooy 🇧🇪 724 122 10ms 11 Jun 2024 857th croc54 724 122 11ms 8 Jan 2025 857th Matter1024 🇮🇳 724 122 9ms 15 Nov 2025 864th janbehrens 🇩🇪 724 130 5ms 23 Jun 2023 864th dokutan 724 130 1ms 8 Nov 2025 866th janbehrens 🇩🇪 724 133 495ms 24 Nov 2022 867th jared-hughes 724 152 414ms 24 Jun 2022 867th Betuaredead 724 152 414ms 7 Jan 2023 869th Shanethegamer 🇺🇸 723 180 40ms 23 Apr 2022 870th MeWhenI 🇻🇦 722 174 41ms 13 Feb 2025 871st GolfingSuccess 🇬🇷 721 43 40ms 22 Jul 2022 871st DialFrost 🇸🇬 721 43 2ms 3 Feb 2024 873rd emgordon154 721 106 465ms 20 Feb 2025 874th Frowny 720 156 146ms 11 Jan 2022 875th msbranicky 720 168 147ms 1 Oct 2023 876th KasperKivimaeki 🇫🇮 719 149 343ms 18 days ago 876th ravnskjaer 🇩🇰 719 149 341ms 15 days ago 878th dokutan 719 153 60ms 8 Nov 2025 879th gitbedd 🇬🇧 718 123 10ms 10 Jan 2022 879th andre-lameirinhas 🇵🇹 718 123 9ms 8 Aug 2022 First Prev 801–880 of 1,570 Next Last
