The Calendar hole will go live in approximately 12 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 640th ridingqwerty 🇺🇸 521 124 16ms 16 Jan 2025 640th CommandLeo 🇮🇹 521 124 9ms 5 Oct 2025 643rd snoozingnewt 🇨🇦 520 213 138ms 2 Nov 2025 644th bac0id 518 180 370ms 9 Jan 2025 645th bnic24 517 125 16ms 3 Oct 2024 645th adoxography 517 125 11ms 22 Oct 2024 645th lelbal 517 125 9ms 14 Oct 2025 648th sidok 515 109 327ms 13 Nov 2024 649th dokutan 514 143 128ms 19 Oct 2024 650th emgordon154 511 156 9ms 13 Dec 2024 651st nephila-nacrea 🇬🇧 510 77 3ms 2 Oct 2024 652nd yoshykai 510 183 364ms 12 Apr 2025 653rd CatsAreFluffy 509 127 15ms 30 Oct 2024 653rd WillowWispy 509 127 10ms 25 May 2025 655th KatieLG 🇬🇧 509 140 392ms 1 Oct 2024 656th KatieLG 🇬🇧 509 146 9ms 2 Oct 2024 657th Chinay-Domitrix 🇺🇸 508 131 4,930ms 30 Mar 2025 658th madex 🇩🇪 501 129 16ms 2 Oct 2024 658th RedzGoose 🇦🇺 501 129 13ms 15 Oct 2024 658th calebaitken 501 129 9ms 11 Apr 2025 658th rollershutter 501 129 17ms 20 Nov 2025 662nd msbranicky 501 138 3ms 3 Oct 2024 663rd snoozingnewt 🇨🇦 501 142 416ms 2 Nov 2025 664th blaztoma 🇱🇹 500 154 127ms 20 days ago 665th MeWhenI 🇻🇦 499 149 55ms 4 Oct 2024 666th janAkali 🇷🇺 499 167 357ms 8 Oct 2024 667th Europe2048 497 130 9ms 2 Oct 2024 667th nstearns96 🇬🇧 497 130 16ms 2 Oct 2024 667th Stockoh 🇫🇷 497 130 16ms 4 Jul 2025 670th inverseLorentz 🇦🇺 493 131 9ms 7 Oct 2024 670th sciencejiho 493 131 16ms 11 Feb 2025 670th Jaydosu 493 131 9ms 11 Apr 2025 670th Emutis 🇱🇹 493 131 9ms 11 Nov 2025 674th CarterStroik 493 161 2ms 19 Nov 2025 675th TheRealOhead 🇺🇸 491 131 9ms 1 Oct 2024 676th HumanoidCPU 491 145 394ms 5 Oct 2024 677th snoozingnewt 🇨🇦 490 150 129ms 2 Nov 2025 678th h-hh-hhh 🇺🇦 487 177 88ms 2 Nov 2024 679th snoozingnewt 🇨🇦 487 249 26ms 2 Nov 2025 680th snoozingnewt 🇨🇦 486 117 904ms 2 Nov 2025 681st Mabeloid 🇳🇴 486 133 9ms 2 Oct 2024 682nd jlangvand 486 141 2ms 15 Oct 2024 682nd HumanoidCPU 486 141 1ms 7 Mar 2025 684th snoozingnewt 🇨🇦 482 173 332ms 2 Nov 2025 685th alphafalfa 480 92 2ms 8 Nov 2024 686th KatieLG 🇬🇧 479 120 476ms 1 Oct 2024 687th mitzal 479 180 90ms 9 Feb 2025 688th sciencedjinn 475 136 9ms 8 Nov 2024 688th ihatethefrench 475 136 16ms 4 Jan 2025 688th Florian-Mt 475 136 19ms 14 days ago 691st MiffOttah 475 150 431ms 6 Oct 2024 692nd kurkale6ka 471 137 21ms 16 Oct 2024 692nd 4ndyJ 🇬🇧 471 137 10ms 14 Nov 2024 692nd Mikey-Beep 🇬🇧 471 137 16ms 6 Aug 2025 692nd wobblybits 471 137 15ms 17 Aug 2025 696th luca1339 471 198 371ms 4 Nov 2024 697th iczelia 🇩🇪 470 94 2ms 23 Sep 2025 698th ejini6969 468 102 49ms 14 Jun 2025 699th h-hh-hhh 🇺🇦 466 147 2ms 2 Nov 2024 700th snoozingnewt 🇨🇦 466 200 228ms 2 Nov 2025 701st scpchicken 🇵🇼 465 139 16ms 6 Oct 2024 702nd snoozingnewt 🇨🇦 464 121 252ms 22 days ago 703rd Jacob385 462 202 358ms 2 Oct 2024 704th NanduBC 461 140 10ms 1 Oct 2024 704th jmerle 🇳🇱 461 140 10ms 10 Jan 2025 704th RobertHoeh 461 140 9ms 3 Mar 2025 704th smilesformiles3 461 140 15ms 12 Jun 2025 704th artem-aramma 461 140 18ms 18 Jun 2025 704th Andrey2001 461 140 10ms 22 days ago 710th snoozingnewt 🇨🇦 460 96 2ms 2 Nov 2025 711th madex 🇩🇪 459 104 34ms 2 Oct 2024 712th FranklinJiaChen 458 141 13ms 2 Oct 2024 713th brimstonetrader 455 142 10ms 17 Oct 2024 713th codewrite 🇬🇧 455 142 11ms 5 May 2025 713th RobGLambert 455 142 16ms 8 Jun 2025 713th GodlyProgrammer1 455 142 16ms 26 days ago 717th snoozingnewt 🇨🇦 454 149 4ms 2 Nov 2025 718th IISResetMe 453 103 516ms 22 days ago 719th TheZwierzLF 🇵🇱 453 127 436ms 7 days ago 720th GeneralFabian 452 143 10ms 9 Dec 2024 First Prev 641–720 of 848 Next Last