The Calendar hole will go live in approximately 13 days. Why not try and solve it ahead of time?
Card Number Validation 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 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 Chars Time Submitted 561st cros107 🇦🇺 587 110 16ms 1 Jan 2025 561st guilhem-roy 🇫🇷 587 110 17ms 29 May 2025 561st Lv0Sys 🇵🇱 587 110 17ms 8 days ago 564th DialFrost 🇸🇬 586 67 8ms 25 Jan 2025 565th roguh 🇬🇹 586 117 1ms 13 Oct 2024 565th iczelia 🇩🇪 586 117 2ms 25 Sep 2025 567th Schmitt-Very-Cool 586 159 440ms 26 Sep 2025 568th gigaprofisi 🇺🇸 585 110 10ms 11 Aug 2025 569th dokutan 584 174 5ms 21 Feb 2025 570th Trip-kun 583 136 2ms 5 Oct 2024 571st mousetail 🇳🇱 582 111 16ms 6 Oct 2024 572nd emgordon154 579 49 3ms 9 days ago 573rd michelebastione 🇮🇹 579 123 404ms 26 Aug 2025 574th dokutan 578 102 785ms 30 Aug 2025 575th MeWhenI 🇻🇦 578 111 88ms 2 Oct 2024 576th OllieBoyne 🇬🇧 577 112 16ms 17 Oct 2024 576th WillConker 577 112 10ms 22 Oct 2024 576th maxgodfrey2004 🇨🇦 577 112 10ms 4 Jan 2025 579th bac0id 576 119 2ms 10 Jan 2025 580th MeWhenI 🇻🇦 576 331 15ms 2 Oct 2024 581st CaedenHarper 🇨🇦 575 100 454ms 22 Jul 2025 582nd 823126 575 112 8ms 13 Nov 2024 582nd snoozingnewt 🇨🇦 575 112 9ms 2 Nov 2025 584th albanian-laundromat 574 77 2ms 3 Nov 2025 585th KatieLG 🇬🇧 574 99 1,081ms 1 Oct 2024 586th MeWhenI 🇻🇦 569 164 181ms 6 Oct 2024 587th CaedenHarper 🇨🇦 567 104 730ms 24 days ago 588th Mabeloid 🇳🇴 567 121 1ms 21 Oct 2025 589th jipsong 🇩🇪 562 115 17ms 12 May 2025 590th aliakseikalosha 561 127 414ms 10 Oct 2024 591st ravnskjaer 🇩🇰 558 167 332ms 3 days ago 592nd rowechenzhong 557 116 9ms 17 Oct 2024 593rd madex 🇩🇪 555 116 9ms 1 Oct 2024 594th FortuiteMan 🇫🇷 554 270 38ms 26 days ago 595th MeWhenI 🇻🇦 554 290 9ms 2 Oct 2024 596th JDiLenarda 🇫🇷 553 165 1,344ms 1 Oct 2024 597th dtbao20 🇻🇳 552 117 16ms 1 Oct 2024 597th Pyroan 552 117 16ms 22 Feb 2025 597th vgamula 🇺🇦 552 117 19ms 5 Aug 2025 597th FortuiteMan 🇫🇷 552 117 20ms 17 days ago 597th yujqiao 552 117 18ms 2 days ago 602nd snoozingnewt 🇨🇦 552 148 122ms 20 Nov 2025 603rd edsrzf 🇳🇿 551 135 6ms 27 Feb 2025 604th msbranicky 550 185 4ms 20 Jan 2025 605th ethanlally 549 170 402ms 19 Nov 2025 605th snoozingnewt 🇨🇦 549 170 435ms 13 days ago 607th gpikmddk 548 130 421ms 30 Oct 2025 608th elgan65536 547 118 10ms 2 Oct 2024 608th logvp 547 118 15ms 6 Oct 2024 608th ahmetdemirag 🇨🇾 547 118 9ms 6 Feb 2025 608th dirckvdende 547 118 19ms 10 Jul 2025 612th zakariamouhid 545 118 9ms 1 Oct 2024 612th JOrE20 🇺🇸 545 118 9ms 17 days ago 614th xyangst 545 171 165ms 1 Oct 2024 614th kmathis22 545 171 430ms 19 Nov 2025 616th najs91 544 131 374ms 15 Oct 2024 616th bac0id 544 131 394ms 9 Jan 2025 616th CaedenHarper 🇨🇦 544 131 375ms 17 Oct 2025 619th jtaxen 543 119 15ms 21 Oct 2024 619th psbpsbp 543 119 9ms 19 Dec 2024 619th klixel 🇨🇦 543 119 9ms 9 Apr 2025 619th vhoulbreque 🇫🇷 543 119 9ms 27 days ago 623rd eranws 541 119 9ms 23 Dec 2024 624th Sciman101 539 147 2ms 26 Mar 2025 625th TaserTheFox 🇺🇸 538 120 16ms 8 Oct 2024 625th yokasuretsu 538 120 10ms 26 Jan 2025 625th Troon 538 120 10ms 17 Feb 2025 628th mousetail 🇳🇱 536 128 2ms 3 Oct 2024 629th BREMAUCY 🇫🇷 534 121 16ms 18 Jul 2025 630th msbranicky 533 175 156ms 13 Dec 2024 631st deancureton 532 121 9ms 30 Dec 2024 632nd chartung17 529 122 10ms 24 Mar 2025 633rd msbranicky 528 126 4,139ms 9 Jan 2025 634th msbranicky 525 123 17ms 3 Oct 2024 634th bobbysq 525 123 10ms 5 Oct 2024 634th wuzekai518 525 123 10ms 8 Oct 2024 637th Macweese 524 178 382ms 3 Aug 2025 638th galloj 🇨🇿 522 112 19ms 4 Oct 2024 639th NotEvenIndian 521 124 10ms 22 Oct 2024 639th ridingqwerty 🇺🇸 521 124 16ms 16 Jan 2025 First Prev 561–640 of 847 Next Last