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 721st snoozingnewt 🇨🇦 501 142 416ms 2 Nov 2025 722nd webmiche 501 159 10ms 3 Nov 2025 723rd blaztoma 🇱🇹 500 154 127ms 20 days ago 724th jlangvand 499 141 2ms 15 Oct 2024 724th HumanoidCPU 499 141 1ms 7 Mar 2025 726th MeWhenI 🇻🇦 499 149 55ms 4 Oct 2024 727th janAkali 🇷🇺 499 167 357ms 8 Oct 2024 728th Mabeloid 🇳🇴 498 133 538ms 2 Oct 2024 729th CheeseCake628 🇳🇴 498 160 102ms 5 Nov 2024 730th pres-abhisheksinha 495 161 10ms 8 Oct 2024 731st CarterStroik 493 161 2ms 19 Nov 2025 732nd ibixina 492 162 9ms 13 Oct 2024 732nd TheAtrossian 492 162 10ms 5 Jan 2025 734th TheRealOhead 🇺🇸 491 131 9ms 1 Oct 2024 735th HumanoidCPU 491 145 394ms 5 Oct 2024 736th snoozingnewt 🇨🇦 490 150 129ms 2 Nov 2025 737th JunkIce 487 136 490ms 3 Dec 2024 738th h-hh-hhh 🇺🇦 487 177 88ms 2 Nov 2024 739th snoozingnewt 🇨🇦 487 249 26ms 2 Nov 2025 740th snoozingnewt 🇨🇦 486 117 904ms 2 Nov 2025 741st Vaekor 483 165 10ms 15 Dec 2024 742nd snoozingnewt 🇨🇦 482 173 332ms 2 Nov 2025 743rd alphafalfa 480 92 2ms 8 Nov 2024 744th mitzal 479 180 90ms 9 Feb 2025 745th h-hh-hhh 🇺🇦 478 147 2ms 2 Nov 2024 746th MiffOttah 475 150 431ms 6 Oct 2024 747th JesseNoEyes 🇺🇸 471 169 10ms 1 Oct 2024 748th luca1339 471 198 371ms 4 Nov 2024 749th Maximizer02 471 201 10ms 1 Oct 2024 750th iczelia 🇩🇪 470 94 2ms 23 Sep 2025 751st zyc-2024 🇨🇳 469 170 9ms 5 Oct 2024 752nd ejini6969 468 102 49ms 14 Jun 2025 753rd ComputerKWasTaken 🇺🇸 466 171 10ms 14 Oct 2024 754th snoozingnewt 🇨🇦 466 200 228ms 2 Nov 2025 755th snoozingnewt 🇨🇦 464 121 252ms 21 days ago 756th Jacob385 462 202 358ms 2 Oct 2024 757th navier-1 461 173 11ms 22 Sep 2025 758th snoozingnewt 🇨🇦 460 96 2ms 2 Nov 2025 759th madex 🇩🇪 459 104 34ms 2 Oct 2024 760th snoozingnewt 🇨🇦 454 149 4ms 2 Nov 2025 761st IISResetMe 453 103 516ms 21 days ago 762nd clayboll99 453 176 10ms 10 Jul 2025 763rd dokutan 451 63 3ms 26 Nov 2024 764th snoozingnewt 🇨🇦 451 176 1ms 2 Nov 2025 765th Upload-and-View 🇺🇦 450 177 17ms 9 Aug 2025 766th varhammer 🇷🇺 450 223 11ms 23 Feb 2025 767th OSYCh314 🇦🇺 448 178 10ms 2 Nov 2024 768th dokutan 445 109 10ms 19 Oct 2024 769th grey0ut 444 105 425ms 11 Jan 2025 770th calum12345 443 180 10ms 26 Mar 2025 771st MyXoToD 🇩🇪 441 146 9ms 26 May 2025 772nd Yewzir 🇧🇪 440 171 12ms 26 Dec 2024 773rd CheeseCake628 🇳🇴 439 151 426ms 18 Oct 2025 774th zt14427 438 182 10ms 27 Dec 2024 775th IoLimmer 435 183 9ms 10 Oct 2024 776th JOrE20 🇺🇸 434 136 754ms 11 days ago 777th KatieLG 🇬🇧 433 183 1ms 2 Oct 2025 778th aksyristos 433 184 16ms 15 Nov 2024 779th KatieLG 🇬🇧 431 108 6ms 13 Oct 2024 780th snoozingnewt 🇨🇦 430 111 41ms 2 Nov 2025 781st estomagordo 🇳🇱 428 186 10ms 15 Jul 2025 782nd snoozingnewt 🇨🇦 427 267 28ms 5 hours ago 783rd dokutan 425 132 331ms 3 Oct 2024 784th MeWhenI 🇻🇦 424 143 6ms 2 Oct 2024 785th Arkadios200 417 196 98ms 21 Oct 2025 786th aksyristos 409 172 2ms 25 days ago 787th dieggsy 406 247 18ms 10 Oct 2024 788th snoozingnewt 🇨🇦 406 313 40ms 2 Nov 2025 789th Mabeloid 🇳🇴 405 159 9ms 12 Oct 2024 790th snoozingnewt 🇨🇦 404 223 75ms 2 Nov 2025 791st Ralac07 🇦🇺 397 162 11ms 3 Oct 2024 792nd snoozingnewt 🇨🇦 392 276 40ms 12 days ago 793rd ehulinsky 🇺🇸 384 158 5ms 2 Apr 2025 794th fischfood 384 176 4ms 22 Oct 2024 795th c0d3-4-F00d 🇩🇪 382 184 2ms 9 Jan 2025 796th snoozingnewt 🇨🇦 376 267 13ms 2 Nov 2025 797th KatieLG 🇬🇧 375 218 108ms 27 days ago 798th RobGLambert 372 232 1,062ms 8 Jun 2025 799th RedzGoose 🇦🇺 369 187 101ms 2 Oct 2024 800th P1nk-P0nk 369 215 3ms 18 Oct 2024 First Prev 721–800 of 850 Next Last