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 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 478th FortuiteMan 🇫🇷 681 117 20ms 17 days ago 478th yujqiao 681 117 18ms 2 days ago 483rd CatsAreFluffy 680 53 49ms 27 Dec 2024 484th Shanethegamer 🇺🇸 679 65 2ms 1 Oct 2024 485th the-zammers 678 163 149ms 1 Dec 2024 486th plcc0 676 37 87ms 6 Apr 2025 487th commandblockguy 🇺🇸 676 98 471ms 1 Sep 2025 488th BlankSpruce 676 104 2ms 1 Oct 2024 489th elgan65536 675 118 10ms 2 Oct 2024 489th logvp 675 118 15ms 6 Oct 2024 489th ahmetdemirag 🇨🇾 675 118 9ms 6 Feb 2025 489th plcc0 675 118 15ms 6 Apr 2025 489th KatieLG 🇬🇧 675 118 16ms 20 Apr 2025 489th dirckvdende 675 118 19ms 10 Jul 2025 495th edsrzf 🇳🇿 673 99 4,316ms 5 Jul 2025 496th tailorspy 673 128 423ms 4 Oct 2024 497th jerrandolph 673 177 285ms 25 Sep 2025 497th CaedenHarper 🇨🇦 673 177 278ms 17 Nov 2025 499th Herbert00709 🇵🇱 670 105 2ms 14 Jun 2025 500th jtaxen 670 119 15ms 21 Oct 2024 500th psbpsbp 670 119 9ms 19 Dec 2024 500th klixel 🇨🇦 670 119 9ms 9 Apr 2025 500th vhoulbreque 🇫🇷 670 119 9ms 27 days ago 504th error256 669 101 4ms 24 Oct 2024 505th CaedenHarper 🇨🇦 666 140 692ms 3 Oct 2025 506th dbut2 🇦🇺 666 179 264ms 31 Oct 2024 507th emgordon154 665 111 4ms 12 Jan 2025 508th two-bad 🇬🇧 664 97 10ms 2 Oct 2024 508th LordSir101 664 97 9ms 10 Aug 2025 510th rniii 664 106 1ms 2 Oct 2024 510th gastropner 664 106 2ms 11 Feb 2025 512th TaserTheFox 🇺🇸 664 120 16ms 8 Oct 2024 512th yokasuretsu 664 120 10ms 26 Jan 2025 512th Troon 664 120 10ms 17 Feb 2025 512th keelimeguy 🇺🇸 664 120 16ms 14 Jun 2025 516th CaedenHarper 🇨🇦 663 100 454ms 22 Jul 2025 517th AlephSquirrel 663 146 4ms 14 May 2025 518th snoozingnewt 🇨🇦 662 180 268ms 2 Nov 2025 519th 4hg 🇺🇸 661 59 34ms 5 Oct 2024 520th DialFrost 🇸🇬 659 67 2ms 22 Dec 2024 521st BREMAUCY 🇫🇷 658 121 16ms 18 Jul 2025 522nd xyangst 657 98 10ms 15 Oct 2024 522nd BambooleanLogic 🇸🇪 657 98 9ms 21 Oct 2024 524th error256 657 142 154ms 31 May 2025 525th jwhear 🇺🇸 655 197 1,696ms 1 Oct 2024 526th chartung17 653 122 10ms 24 Mar 2025 527th w911 651 183 268ms 7 Oct 2024 528th albanian-laundromat 651 293 14ms 10 days ago 529th Babafaba 650 102 436ms 11 Nov 2025 530th MeWhenI 🇻🇦 648 91 704ms 29 Aug 2025 531st msbranicky 648 123 17ms 3 Oct 2024 531st bobbysq 648 123 10ms 5 Oct 2024 531st wuzekai518 648 123 10ms 8 Oct 2024 534th rucin93 🇵🇱 648 144 143ms 28 Oct 2024 535th koipondx86 645 123 2ms 8 Nov 2024 536th CaedenHarper 🇨🇦 644 100 9ms 22 Aug 2025 536th iczelia 🇩🇪 644 100 9ms 11 Oct 2025 536th Yax42 🇫🇷 644 100 9ms 21 days ago 539th NotEvenIndian 643 124 10ms 22 Oct 2024 539th ridingqwerty 🇺🇸 643 124 16ms 16 Jan 2025 539th CommandLeo 🇮🇹 643 124 9ms 5 Oct 2025 542nd Apataras 643 145 381ms 25 Jun 2025 543rd tomh1012 641 111 441ms 8 Sep 2025 544th stefangimmillaro 639 73 301ms 1 Oct 2024 545th Jonatan6 🇩🇰 639 110 2ms 24 Oct 2024 545th solisolu 639 110 2ms 23 days ago 547th elgan65536 639 146 147ms 2 Oct 2024 547th dokutan 639 146 382ms 24 days ago 547th luuumine 🇫🇷 639 146 146ms 22 days ago 550th MeWhenI 🇻🇦 638 73 8ms 3 Oct 2024 551st bnic24 637 125 16ms 3 Oct 2024 551st adoxography 637 125 11ms 22 Oct 2024 551st wh3n3v3r 🇨🇿 637 125 10ms 18 Nov 2024 551st lelbal 637 125 9ms 14 Oct 2025 555th msbranicky 634 188 296ms 7 Jan 2025 556th Shanethegamer 🇺🇸 631 74 278ms 16 Oct 2024 557th XenThe 🇬🇧 631 102 9ms 7 Jul 2025 557th Florian-Mt 631 102 9ms 12 days ago 559th albanian-laundromat 631 264 492ms 3 Nov 2025 560th CatsAreFluffy 627 127 15ms 30 Oct 2024 First Prev 481–560 of 849 Next Last