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 jlangvand 499 141 2ms 15 Oct 2024 723rd HumanoidCPU 499 141 1ms 7 Mar 2025 725th MeWhenI 🇻🇦 499 149 55ms 4 Oct 2024 726th janAkali 🇷🇺 499 167 357ms 8 Oct 2024 727th Mabeloid 🇳🇴 498 133 538ms 2 Oct 2024 728th CheeseCake628 🇳🇴 498 160 102ms 5 Nov 2024 729th pres-abhisheksinha 495 161 10ms 8 Oct 2024 730th CarterStroik 493 161 2ms 19 Nov 2025 731st ibixina 492 162 9ms 13 Oct 2024 731st TheAtrossian 492 162 10ms 5 Jan 2025 733rd TheRealOhead 🇺🇸 491 131 9ms 1 Oct 2024 734th HumanoidCPU 491 145 394ms 5 Oct 2024 735th snoozingnewt 🇨🇦 490 150 129ms 2 Nov 2025 736th JunkIce 487 136 490ms 3 Dec 2024 737th h-hh-hhh 🇺🇦 487 177 88ms 2 Nov 2024 738th snoozingnewt 🇨🇦 487 249 26ms 2 Nov 2025 739th snoozingnewt 🇨🇦 486 117 904ms 2 Nov 2025 740th Vaekor 483 165 10ms 15 Dec 2024 741st snoozingnewt 🇨🇦 482 173 332ms 2 Nov 2025 742nd alphafalfa 480 92 2ms 8 Nov 2024 743rd mitzal 479 180 90ms 9 Feb 2025 744th h-hh-hhh 🇺🇦 478 147 2ms 2 Nov 2024 745th MiffOttah 475 150 431ms 6 Oct 2024 746th JesseNoEyes 🇺🇸 471 169 10ms 1 Oct 2024 747th luca1339 471 198 371ms 4 Nov 2024 748th Maximizer02 471 201 10ms 1 Oct 2024 749th iczelia 🇩🇪 470 94 2ms 23 Sep 2025 750th zyc-2024 🇨🇳 469 170 9ms 5 Oct 2024 751st ejini6969 468 102 49ms 14 Jun 2025 752nd ComputerKWasTaken 🇺🇸 466 171 10ms 14 Oct 2024 753rd snoozingnewt 🇨🇦 466 200 228ms 2 Nov 2025 754th snoozingnewt 🇨🇦 464 121 252ms 21 days ago 755th Jacob385 462 202 358ms 2 Oct 2024 756th navier-1 461 173 11ms 22 Sep 2025 757th snoozingnewt 🇨🇦 460 96 2ms 2 Nov 2025 758th madex 🇩🇪 459 104 34ms 2 Oct 2024 759th snoozingnewt 🇨🇦 454 149 4ms 2 Nov 2025 760th IISResetMe 453 103 516ms 21 days ago 761st clayboll99 453 176 10ms 10 Jul 2025 762nd dokutan 451 63 3ms 26 Nov 2024 763rd snoozingnewt 🇨🇦 451 176 1ms 2 Nov 2025 764th Upload-and-View 🇺🇦 450 177 17ms 9 Aug 2025 765th varhammer 🇷🇺 450 223 11ms 23 Feb 2025 766th OSYCh314 🇦🇺 448 178 10ms 2 Nov 2024 767th dokutan 445 109 10ms 19 Oct 2024 768th grey0ut 444 105 425ms 11 Jan 2025 769th calum12345 443 180 10ms 26 Mar 2025 770th MyXoToD 🇩🇪 441 146 9ms 26 May 2025 771st Yewzir 🇧🇪 440 171 12ms 26 Dec 2024 772nd CheeseCake628 🇳🇴 439 151 426ms 18 Oct 2025 773rd zt14427 438 182 10ms 27 Dec 2024 774th IoLimmer 435 183 9ms 10 Oct 2024 775th JOrE20 🇺🇸 434 136 754ms 11 days ago 776th KatieLG 🇬🇧 433 183 1ms 2 Oct 2025 777th aksyristos 433 184 16ms 15 Nov 2024 778th KatieLG 🇬🇧 431 108 6ms 13 Oct 2024 779th snoozingnewt 🇨🇦 430 111 41ms 2 Nov 2025 780th estomagordo 🇳🇱 428 186 10ms 15 Jul 2025 781st snoozingnewt 🇨🇦 427 267 28ms 2 hours ago 782nd dokutan 425 132 331ms 3 Oct 2024 783rd MeWhenI 🇻🇦 424 143 6ms 2 Oct 2024 784th Arkadios200 417 196 98ms 21 Oct 2025 785th aksyristos 409 172 2ms 25 days ago 786th dieggsy 406 247 18ms 10 Oct 2024 787th snoozingnewt 🇨🇦 406 313 40ms 2 Nov 2025 788th Mabeloid 🇳🇴 405 159 9ms 12 Oct 2024 789th snoozingnewt 🇨🇦 404 223 75ms 2 Nov 2025 790th Ralac07 🇦🇺 397 162 11ms 3 Oct 2024 791st snoozingnewt 🇨🇦 392 276 40ms 11 days ago 792nd ehulinsky 🇺🇸 384 158 5ms 2 Apr 2025 793rd fischfood 384 176 4ms 22 Oct 2024 794th c0d3-4-F00d 🇩🇪 382 184 2ms 9 Jan 2025 795th snoozingnewt 🇨🇦 376 267 13ms 2 Nov 2025 796th KatieLG 🇬🇧 375 218 108ms 26 days ago 797th RobGLambert 372 232 1,062ms 8 Jun 2025 798th RedzGoose 🇦🇺 369 187 101ms 2 Oct 2024 799th P1nk-P0nk 369 215 3ms 18 Oct 2024 800th gautambp 365 218 11ms 24 Jun 2025 First Prev 721–800 of 849 Next Last