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 801st RobGLambert 342 273 183ms 8 Jun 2025 802nd Ernest1338 339 275 265ms 26 Oct 2024 803rd noahhorlacher 337 191 9ms 7 Dec 2024 804th JOrE20 🇺🇸 312 389 56ms 14 days ago 805th snoozingnewt 🇨🇦 303 200 3ms 2 Nov 2025 806th KatieLG 🇬🇧 297 290 2,538ms 1 Oct 2025 807th gautambp 296 218 11ms 24 Jun 2025 808th KatieLG 🇬🇧 284 241 2ms 1 Oct 2025 809th Zhenyu-Bo 283 228 10ms 30 Jul 2025 810th EthanJantz 281 230 10ms 5 Sep 2025 811th ReterikHub 278 310 199ms 17 Jan 2025 812th RobertBurs 273 237 10ms 22 Sep 2025 813th Mikey-Beep 🇬🇧 273 349 14ms 12 Aug 2025 814th MeWhenI 🇻🇦 272 407 119ms 6 Oct 2024 815th TJK-S 268 241 10ms 25 Oct 2025 816th te-chnical 250 258 215ms 4 May 2025 817th NoneTheFewer 245 264 11ms 9 days ago 818th arebbsba 218 296 10ms 9 Jan 2025 819th Msleizak 🇫🇷 206 226 294ms 19 May 2025 820th AidanWalter 120 540 10ms 1 Jan 2025 821st vkptimon 120 776 415ms 9 Jul 2025 822nd bignamehyp 97 667 13ms 14 Nov 2024 823rd dokutan 60 2,474 123ms 18 Aug 2025 824th iczelia 🇩🇪 52 2,045 4ms 14 Oct 2025 825th lyphyser 0 15 114ms 25 May 2025 826th 2bular 0 16 84ms 22 Mar 2025 826th namelessiw 0 16 141ms 19 Nov 2025 828th darrenks 0 17 93ms 22 Mar 2025 829th Natanaelel 🇸🇪 0 18 79ms 23 Mar 2025 829th lyxal 🇦🇺 0 18 682ms 17 May 2025 829th themoonisacheese 0 18 632ms 13 Jun 2025 832nd kg583 🇺🇸 0 20 265ms 14 May 2025 833rd plcc0 0 21 91ms 4 Apr 2025 834th ovs-code 🇩🇪 0 37 2ms 13 Jul 2025 835th maweowo 🇩🇪 0 39 4ms 2 Oct 2025 836th ovs-code 🇩🇪 0 40 7ms 9 Jul 2025 837th AlephSquirrel 0 43 3ms 15 Jun 2025 838th evnu 0 44 5ms 12 Oct 2025 839th ovs-code 🇩🇪 0 51 16ms 13 Jun 2025 840th GrayJoKing 🇦🇺 0 55 4ms 13 Jul 2025 841st chunes3 🇺🇸 0 65 7ms 13 Feb 2025 842nd DialFrost 🇸🇬 0 66 11ms 14 days ago 843rd sean-niemann 🇺🇸 0 68 58ms 30 Apr 2025 844th dokutan 0 89 60ms 28 Jun 2025 845th MatthewF19 0 108 113ms 17 May 2025 846th albanian-laundromat 0 123 2ms 4 Jun 2025 847th edsrzf 🇳🇿 0 142 183ms 24 Jul 2025 First Prev 801–847 of 847