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 639th CommandLeo 🇮🇹 521 124 9ms 5 Oct 2025 642nd snoozingnewt 🇨🇦 520 213 138ms 2 Nov 2025 643rd bac0id 518 180 370ms 9 Jan 2025 644th bnic24 517 125 16ms 3 Oct 2024 644th adoxography 517 125 11ms 22 Oct 2024 644th lelbal 517 125 9ms 14 Oct 2025 647th sidok 515 109 327ms 13 Nov 2024 648th dokutan 514 143 128ms 19 Oct 2024 649th emgordon154 511 156 9ms 13 Dec 2024 650th nephila-nacrea 🇬🇧 510 77 3ms 2 Oct 2024 651st yoshykai 510 183 364ms 12 Apr 2025 652nd CatsAreFluffy 509 127 15ms 30 Oct 2024 652nd WillowWispy 509 127 10ms 25 May 2025 654th KatieLG 🇬🇧 509 140 392ms 1 Oct 2024 655th KatieLG 🇬🇧 509 146 9ms 2 Oct 2024 656th Chinay-Domitrix 🇺🇸 508 131 4,930ms 30 Mar 2025 657th madex 🇩🇪 501 129 16ms 2 Oct 2024 657th RedzGoose 🇦🇺 501 129 13ms 15 Oct 2024 657th calebaitken 501 129 9ms 11 Apr 2025 657th rollershutter 501 129 17ms 20 Nov 2025 661st msbranicky 501 138 3ms 3 Oct 2024 662nd snoozingnewt 🇨🇦 501 142 416ms 2 Nov 2025 663rd blaztoma 🇱🇹 500 154 127ms 20 days ago 664th MeWhenI 🇻🇦 499 149 55ms 4 Oct 2024 665th janAkali 🇷🇺 499 167 357ms 8 Oct 2024 666th Europe2048 497 130 9ms 2 Oct 2024 666th nstearns96 🇬🇧 497 130 16ms 2 Oct 2024 666th Stockoh 🇫🇷 497 130 16ms 4 Jul 2025 669th inverseLorentz 🇦🇺 493 131 9ms 7 Oct 2024 669th sciencejiho 493 131 16ms 11 Feb 2025 669th Jaydosu 493 131 9ms 11 Apr 2025 669th Emutis 🇱🇹 493 131 9ms 11 Nov 2025 673rd CarterStroik 493 161 2ms 19 Nov 2025 674th TheRealOhead 🇺🇸 491 131 9ms 1 Oct 2024 675th HumanoidCPU 491 145 394ms 5 Oct 2024 676th snoozingnewt 🇨🇦 490 150 129ms 2 Nov 2025 677th h-hh-hhh 🇺🇦 487 177 88ms 2 Nov 2024 678th snoozingnewt 🇨🇦 487 249 26ms 2 Nov 2025 679th snoozingnewt 🇨🇦 486 117 904ms 2 Nov 2025 680th Mabeloid 🇳🇴 486 133 9ms 2 Oct 2024 681st jlangvand 486 141 2ms 15 Oct 2024 681st HumanoidCPU 486 141 1ms 7 Mar 2025 683rd snoozingnewt 🇨🇦 482 173 332ms 2 Nov 2025 684th alphafalfa 480 92 2ms 8 Nov 2024 685th KatieLG 🇬🇧 479 120 476ms 1 Oct 2024 686th mitzal 479 180 90ms 9 Feb 2025 687th sciencedjinn 475 136 9ms 8 Nov 2024 687th ihatethefrench 475 136 16ms 4 Jan 2025 687th Florian-Mt 475 136 19ms 13 days ago 690th MiffOttah 475 150 431ms 6 Oct 2024 691st kurkale6ka 471 137 21ms 16 Oct 2024 691st 4ndyJ 🇬🇧 471 137 10ms 14 Nov 2024 691st Mikey-Beep 🇬🇧 471 137 16ms 6 Aug 2025 691st wobblybits 471 137 15ms 17 Aug 2025 695th luca1339 471 198 371ms 4 Nov 2024 696th iczelia 🇩🇪 470 94 2ms 23 Sep 2025 697th ejini6969 468 102 49ms 14 Jun 2025 698th h-hh-hhh 🇺🇦 466 147 2ms 2 Nov 2024 699th snoozingnewt 🇨🇦 466 200 228ms 2 Nov 2025 700th scpchicken 🇵🇼 465 139 16ms 6 Oct 2024 701st snoozingnewt 🇨🇦 464 121 252ms 21 days ago 702nd Jacob385 462 202 358ms 2 Oct 2024 703rd NanduBC 461 140 10ms 1 Oct 2024 703rd jmerle 🇳🇱 461 140 10ms 10 Jan 2025 703rd RobertHoeh 461 140 9ms 3 Mar 2025 703rd smilesformiles3 461 140 15ms 12 Jun 2025 703rd artem-aramma 461 140 18ms 18 Jun 2025 703rd Andrey2001 461 140 10ms 21 days ago 709th snoozingnewt 🇨🇦 460 96 2ms 2 Nov 2025 710th madex 🇩🇪 459 104 34ms 2 Oct 2024 711th FranklinJiaChen 458 141 13ms 2 Oct 2024 712th brimstonetrader 455 142 10ms 17 Oct 2024 712th codewrite 🇬🇧 455 142 11ms 5 May 2025 712th RobGLambert 455 142 16ms 8 Jun 2025 712th GodlyProgrammer1 455 142 16ms 25 days ago 716th snoozingnewt 🇨🇦 454 149 4ms 2 Nov 2025 717th IISResetMe 453 103 516ms 21 days ago 718th TheZwierzLF 🇵🇱 453 127 436ms 6 days ago 719th GeneralFabian 452 143 10ms 9 Dec 2024 719th CutSandstone 452 143 9ms 30 Jan 2025 First Prev 641–720 of 847 Next Last