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 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 479th vgamula 🇺🇦 681 117 19ms 5 Aug 2025 479th FortuiteMan 🇫🇷 681 117 20ms 18 days ago 479th yujqiao 681 117 18ms 3 days ago 484th CatsAreFluffy 680 53 49ms 27 Dec 2024 485th the-zammers 680 163 149ms 1 Dec 2024 486th Shanethegamer 🇺🇸 679 65 2ms 1 Oct 2024 487th plcc0 676 37 87ms 6 Apr 2025 488th commandblockguy 🇺🇸 676 98 471ms 1 Sep 2025 489th BlankSpruce 676 104 2ms 1 Oct 2024 490th elgan65536 675 118 10ms 2 Oct 2024 490th logvp 675 118 15ms 6 Oct 2024 490th ahmetdemirag 🇨🇾 675 118 9ms 6 Feb 2025 490th plcc0 675 118 15ms 6 Apr 2025 490th KatieLG 🇬🇧 675 118 16ms 20 Apr 2025 490th dirckvdende 675 118 19ms 10 Jul 2025 496th edsrzf 🇳🇿 673 99 4,316ms 5 Jul 2025 497th tailorspy 673 128 423ms 4 Oct 2024 498th jerrandolph 673 177 285ms 25 Sep 2025 498th CaedenHarper 🇨🇦 673 177 278ms 17 Nov 2025 500th Herbert00709 🇵🇱 670 105 2ms 14 Jun 2025 501st emgordon154 670 115 95ms 10 days ago 502nd jtaxen 670 119 15ms 21 Oct 2024 502nd psbpsbp 670 119 9ms 19 Dec 2024 502nd klixel 🇨🇦 670 119 9ms 9 Apr 2025 502nd vhoulbreque 🇫🇷 670 119 9ms 21 Nov 2025 506th error256 669 101 4ms 24 Oct 2024 507th CaedenHarper 🇨🇦 666 140 692ms 3 Oct 2025 508th dbut2 🇦🇺 666 179 264ms 31 Oct 2024 509th emgordon154 665 111 4ms 12 Jan 2025 510th two-bad 🇬🇧 664 97 10ms 2 Oct 2024 510th LordSir101 664 97 9ms 10 Aug 2025 512th rniii 664 106 1ms 2 Oct 2024 512th gastropner 664 106 2ms 11 Feb 2025 514th TaserTheFox 🇺🇸 664 120 16ms 8 Oct 2024 514th yokasuretsu 664 120 10ms 26 Jan 2025 514th Troon 664 120 10ms 17 Feb 2025 514th keelimeguy 🇺🇸 664 120 16ms 14 Jun 2025 518th CaedenHarper 🇨🇦 663 100 454ms 22 Jul 2025 519th snoozingnewt 🇨🇦 662 180 268ms 2 Nov 2025 520th 4hg 🇺🇸 661 59 34ms 5 Oct 2024 521st DialFrost 🇸🇬 659 67 2ms 22 Dec 2024 522nd BREMAUCY 🇫🇷 658 121 16ms 18 Jul 2025 523rd xyangst 657 98 10ms 15 Oct 2024 523rd BambooleanLogic 🇸🇪 657 98 9ms 21 Oct 2024 525th error256 657 142 154ms 31 May 2025 526th AlephSquirrel 657 146 4ms 14 May 2025 527th jwhear 🇺🇸 655 197 1,696ms 1 Oct 2024 528th chartung17 653 122 10ms 24 Mar 2025 529th w911 651 183 268ms 7 Oct 2024 530th albanian-laundromat 651 293 14ms 11 days ago 531st Babafaba 650 102 436ms 11 Nov 2025 532nd MeWhenI 🇻🇦 648 91 704ms 29 Aug 2025 533rd msbranicky 648 123 17ms 3 Oct 2024 533rd bobbysq 648 123 10ms 5 Oct 2024 533rd wuzekai518 648 123 10ms 8 Oct 2024 536th rucin93 🇵🇱 648 144 143ms 28 Oct 2024 537th koipondx86 645 123 2ms 8 Nov 2024 538th CaedenHarper 🇨🇦 644 100 9ms 22 Aug 2025 538th iczelia 🇩🇪 644 100 9ms 11 Oct 2025 538th Yax42 🇫🇷 644 100 9ms 22 days ago 541st NotEvenIndian 643 124 10ms 22 Oct 2024 541st ridingqwerty 🇺🇸 643 124 16ms 16 Jan 2025 541st CommandLeo 🇮🇹 643 124 9ms 5 Oct 2025 544th Apataras 643 145 381ms 25 Jun 2025 545th tomh1012 641 111 441ms 8 Sep 2025 546th stefangimmillaro 639 73 301ms 1 Oct 2024 547th Jonatan6 🇩🇰 639 110 2ms 24 Oct 2024 547th solisolu 639 110 2ms 24 days ago 549th elgan65536 639 146 147ms 2 Oct 2024 549th dokutan 639 146 382ms 26 days ago 549th luuumine 🇫🇷 639 146 146ms 23 days ago 552nd MeWhenI 🇻🇦 638 73 8ms 3 Oct 2024 553rd bnic24 637 125 16ms 3 Oct 2024 553rd adoxography 637 125 11ms 22 Oct 2024 553rd wh3n3v3r 🇨🇿 637 125 10ms 18 Nov 2024 553rd lelbal 637 125 9ms 14 Oct 2025 557th msbranicky 634 188 296ms 7 Jan 2025 558th Shanethegamer 🇺🇸 631 74 278ms 16 Oct 2024 559th XenThe 🇬🇧 631 102 9ms 7 Jul 2025 559th Florian-Mt 631 102 9ms 14 days ago First Prev 481–560 of 851 Next Last