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 801st sciencejiho 357 197 2ms 11 Feb 2025 802nd The-Wolfson 355 230 100ms 16 Dec 2024 803rd JOrE20 🇺🇸 354 208 120ms 11 days ago 804th Zhenyu-Bo 349 228 10ms 30 Jul 2025 805th EthanJantz 346 230 10ms 5 Sep 2025 806th RobGLambert 342 273 183ms 8 Jun 2025 807th Ernest1338 339 275 265ms 26 Oct 2024 808th noahhorlacher 337 191 9ms 7 Dec 2024 809th RobertBurs 336 237 10ms 22 Sep 2025 810th TJK-S 331 241 10ms 25 Oct 2025 811th JOrE20 🇺🇸 312 389 56ms 14 days ago 812th te-chnical 309 258 215ms 4 May 2025 813th snoozingnewt 🇨🇦 303 200 3ms 2 Nov 2025 814th NoneTheFewer 302 264 11ms 9 days ago 815th KatieLG 🇬🇧 297 290 2,538ms 1 Oct 2025 816th KatieLG 🇬🇧 292 241 2ms 1 Oct 2025 817th ReterikHub 278 310 199ms 17 Jan 2025 818th Mikey-Beep 🇬🇧 273 349 14ms 12 Aug 2025 819th MeWhenI 🇻🇦 271 407 119ms 6 Oct 2024 820th arebbsba 269 296 10ms 9 Jan 2025 821st Msleizak 🇫🇷 206 226 294ms 19 May 2025 822nd AidanWalter 148 540 10ms 1 Jan 2025 823rd vkptimon 120 776 415ms 9 Jul 2025 824th bignamehyp 119 667 13ms 14 Nov 2024 825th dokutan 61 2,475 123ms 18 Aug 2025 826th iczelia 🇩🇪 52 2,045 4ms 14 Oct 2025 827th lyphyser 0 15 114ms 25 May 2025 828th 2bular 0 16 84ms 22 Mar 2025 829th darrenks 0 17 93ms 22 Mar 2025 830th Natanaelel 🇸🇪 0 18 79ms 23 Mar 2025 831st plcc0 0 21 91ms 4 Apr 2025 831st namelessiw 0 21 150ms 19 Nov 2025 833rd kg583 🇺🇸 0 25 274ms 8 Feb 2025 834th lyxal 🇦🇺 0 27 681ms 17 May 2025 835th themoonisacheese 0 35 632ms 13 Jun 2025 836th ovs-code 🇩🇪 0 54 4ms 9 Jul 2025 837th GrayJoKing 🇦🇺 0 55 4ms 13 Jul 2025 838th ovs-code 🇩🇪 0 58 2ms 13 Jul 2025 839th AlephSquirrel 0 63 3ms 15 Jun 2025 840th DialFrost 🇸🇬 0 68 11ms 14 days ago 841st chunes3 🇺🇸 0 69 7ms 13 Feb 2025 842nd maweowo 🇩🇪 0 70 4ms 2 Oct 2025 843rd evnu 0 73 6ms 12 Oct 2025 844th ovs-code 🇩🇪 0 76 15ms 13 Jun 2025 845th sean-niemann 🇺🇸 0 80 59ms 29 Apr 2025 846th albanian-laundromat 0 123 2ms 4 Jun 2025 847th edsrzf 🇳🇿 0 142 183ms 24 Jul 2025 848th MatthewF19 0 192 113ms 17 May 2025 849th dokutan 0 219 60ms 28 Jun 2025 First Prev 801–849 of 849
