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 721st snoozingnewt 🇨🇦 451 176 1ms 2 Nov 2025 722nd varhammer 🇷🇺 450 223 11ms 23 Feb 2025 723rd hiichbindermax 449 144 15ms 2 Oct 2024 723rd mathisfun271 449 144 9ms 14 Oct 2024 723rd bob-th 449 144 10ms 22 Oct 2024 726th dokutan 445 109 10ms 19 Oct 2024 727th Flekay 🇩🇪 445 145 10ms 10 Jul 2025 728th grey0ut 444 105 425ms 11 Jan 2025 729th croc54 442 146 12ms 15 Dec 2024 730th MyXoToD 🇩🇪 441 146 9ms 26 May 2025 731st Yewzir 🇧🇪 440 171 12ms 26 Dec 2024 732nd PyryL 🇫🇮 439 147 10ms 1 Mar 2025 733rd mbittner20 436 148 11ms 13 Oct 2024 733rd YAJUE114514 436 148 10ms 6 days ago 735th Andrey2001 435 132 720ms 20 days ago 736th JOrE20 🇺🇸 434 136 754ms 10 days ago 737th psaban 434 149 16ms 31 Jul 2025 737th TheZwierzLF 🇵🇱 434 149 11ms 23 days ago 739th KatieLG 🇬🇧 433 183 1ms 2 Oct 2025 740th dokutan 432 130 401ms 17 Oct 2024 741st Mabeloid 🇳🇴 432 133 538ms 2 Oct 2024 742nd KatieLG 🇬🇧 431 108 6ms 13 Oct 2024 743rd jameswmccarty 431 150 10ms 5 Oct 2024 743rd yousefalizadeh 431 150 10ms 23 Oct 2024 743rd feherd 431 150 10ms 31 Oct 2024 743rd kadamkaustubh 431 150 9ms 8 Nov 2025 747th snoozingnewt 🇨🇦 430 111 41ms 2 Nov 2025 748th snoozingnewt 🇨🇦 426 268 27ms 2 Nov 2025 749th adamnielson42 🇺🇸 425 152 12ms 6 Oct 2024 749th voidgloom 425 152 10ms 22 Oct 2024 749th omero-san 425 152 9ms 22 Sep 2025 749th brochmann 🇸🇪 425 152 13ms 12 Oct 2025 753rd MeWhenI 🇻🇦 424 143 6ms 2 Oct 2024 754th denisfouchard 422 153 10ms 21 Aug 2025 755th osNiko 🇧🇷 419 154 11ms 21 Aug 2025 756th celiendonze 🇨🇭 417 155 11ms 17 Oct 2025 757th Arkadios200 417 196 98ms 21 Oct 2025 758th Shotokhan 414 156 9ms 21 Sep 2025 759th lhulinsky 411 157 9ms 21 Oct 2024 760th ThatAlo 409 158 10ms 9 Dec 2024 761st webmiche 406 159 10ms 3 Nov 2025 762nd dieggsy 406 247 18ms 10 Oct 2024 763rd Mabeloid 🇳🇴 405 159 9ms 12 Oct 2024 764th CheeseCake628 🇳🇴 404 160 102ms 5 Nov 2024 765th snoozingnewt 🇨🇦 404 223 75ms 2 Nov 2025 766th pres-abhisheksinha 401 161 10ms 8 Oct 2024 767th ibixina 399 162 9ms 13 Oct 2024 767th TheAtrossian 399 162 10ms 5 Jan 2025 769th aksyristos 399 172 2ms 24 days ago 770th Ralac07 🇦🇺 397 162 11ms 3 Oct 2024 771st Maximizer02 396 201 10ms 1 Oct 2024 772nd snoozingnewt 🇨🇦 392 276 40ms 11 days ago 773rd Vaekor 391 165 10ms 15 Dec 2024 774th ehulinsky 🇺🇸 384 158 5ms 2 Apr 2025 775th fischfood 384 176 4ms 22 Oct 2024 776th JesseNoEyes 🇺🇸 382 169 10ms 1 Oct 2024 777th CheeseCake628 🇳🇴 381 151 426ms 18 Oct 2025 778th zyc-2024 🇨🇳 380 170 9ms 5 Oct 2024 779th ComputerKWasTaken 🇺🇸 378 171 10ms 14 Oct 2024 780th snoozingnewt 🇨🇦 376 267 13ms 2 Nov 2025 781st KatieLG 🇬🇧 375 218 108ms 26 days ago 782nd navier-1 373 173 11ms 22 Sep 2025 783rd c0d3-4-F00d 🇩🇪 373 184 2ms 9 Jan 2025 784th RobGLambert 372 232 1,062ms 8 Jun 2025 785th snoozingnewt 🇨🇦 372 313 40ms 2 Nov 2025 786th RedzGoose 🇦🇺 369 187 101ms 2 Oct 2024 787th P1nk-P0nk 369 215 3ms 18 Oct 2024 788th clayboll99 367 176 10ms 10 Jul 2025 789th Upload-and-View 🇺🇦 365 177 17ms 9 Aug 2025 790th OSYCh314 🇦🇺 363 178 10ms 2 Nov 2024 791st calum12345 359 180 10ms 26 Mar 2025 792nd zt14427 355 182 10ms 27 Dec 2024 793rd The-Wolfson 355 230 100ms 16 Dec 2024 794th JOrE20 🇺🇸 354 208 120ms 10 days ago 795th IoLimmer 353 183 9ms 10 Oct 2024 796th aksyristos 351 184 16ms 15 Nov 2024 797th sciencejiho 348 197 2ms 11 Feb 2025 798th estomagordo 🇳🇱 347 186 10ms 15 Jul 2025 799th RobGLambert 342 273 183ms 8 Jun 2025 800th Ernest1338 339 275 265ms 26 Oct 2024 First Prev 721–800 of 845 Next Last