The Calendar hole will go live in approximately 2 days. Why not try and solve it ahead of time?
Collatz 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 800th Schmitt-Very-Cool 857 97 435ms 26 Sep 2025 802nd typeswitch-dev 🇵🇹 856 75 5ms 22 Jul 2023 803rd ovs-code 🇩🇪 856 83 54ms 1 Jul 2024 804th 386asm 🇺🇸 856 86 40ms 9 Apr 2023 805th nwellnhof 🇩🇪 856 111 271ms 4 May 2022 805th stefangimmillaro 856 111 268ms 26 Sep 2023 805th kkoenig 856 111 287ms 4 Jan 2024 808th frankgraziano 856 198 108ms 14 Oct 2025 809th Frowny 855 38 40ms 5 May 2022 809th stackofbears 855 38 42ms 14 Mar 2025 811th dokutan 855 79 11ms 27 Apr 2024 812th DialFrost 🇸🇬 854 50 253ms 24 Oct 2023 813th Shanethegamer 🇺🇸 854 70 99ms 12 Dec 2022 813th Alessandro-Balconi 🇮🇹 854 70 95ms 26 Dec 2022 813th snoozingnewt 🇨🇦 854 70 207ms 22 Nov 2025 816th henrydukepickle 854 97 118ms 8 Jul 2025 817th yeminghan2021 854 99 66ms 3 Feb 2025 818th aditsu 853 77 3,141ms 23 Nov 2025 819th eshilo-draper 853 91 365ms 4 Sep 2022 819th ericlangedijk 🇸🇮 853 91 389ms 23 May 2023 819th KatieLG 🇬🇧 853 91 363ms 30 Apr 2024 819th Mikey-Beep 🇬🇧 853 91 341ms 3 Sep 2024 823rd ovs-code 🇩🇪 853 161 1,719ms 14 Sep 2025 824th Shanethegamer 🇺🇸 852 83 1,354ms 4 May 2022 825th MeWhenI 🇻🇦 852 92 398ms 10 Oct 2022 825th Betuaredead 852 92 468ms 5 Jan 2023 825th Yax42 🇫🇷 852 92 420ms 4 Oct 2025 828th o0lit3 🇺🇸 851 54 7ms 22 Jun 2023 828th Natanaelel 🇸🇪 851 54 7ms 10 Feb 2025 830th Shanethegamer 🇺🇸 851 58 767ms 17 Sep 2025 831st Yewzir 🇧🇪 851 65 4ms 9 Oct 2023 831st MeWhenI 🇻🇦 851 65 3ms 10 Oct 2023 833rd SirBogman 🇺🇸 850 55 41ms 5 May 2022 833rd olivermrose 🇺🇸 850 55 45ms 6 May 2022 833rd 4hg 🇺🇸 850 55 43ms 24 Aug 2022 833rd DialFrost 🇸🇬 850 55 45ms 1 Jan 2023 833rd error256 850 55 40ms 4 May 2024 838th mtirado1 850 74 83ms 24 Dec 2022 838th Betuaredead 850 74 81ms 6 Jan 2023 838th KatieLG 🇬🇧 850 74 81ms 15 Jan 2023 838th bwat2 850 74 84ms 31 Mar 2023 838th stackotter 850 74 82ms 29 May 2023 838th ovs-code 🇩🇪 850 74 82ms 17 Apr 2024 838th madeforlosers 850 74 80ms 21 Nov 2024 845th Shanethegamer 🇺🇸 850 99 24ms 27 Apr 2023 846th JayXon 🇺🇸 848 56 998ms 9 May 2022 847th DialFrost 🇸🇬 848 162 1,753ms 13 Sep 2025 848th the-zammers 847 68 172ms 2 Oct 2023 849th MeWhenI 🇻🇦 846 26 163ms 25 Aug 2022 849th AlephSquirrel 846 26 209ms 6 Jan 2023 849th ovs-code 🇩🇪 846 26 378ms 5 May 2024 849th saito-ta 🇯🇵 846 26 156ms 12 Dec 2024 853rd randolchance 846 63 11ms 8 Jan 2023 853rd CatsAreFluffy 846 63 10ms 18 Feb 2023 853rd amiralitaheri 846 63 10ms 23 Feb 2023 853rd RuyiLi 846 63 9ms 1 Apr 2023 853rd TaserTheFox 🇺🇸 846 63 10ms 25 May 2023 853rd pfysches-boop 846 63 9ms 6 Aug 2023 853rd mhgockel 846 63 10ms 19 Aug 2023 853rd NickTheEASDude 🇺🇸 846 63 10ms 18 Jan 2024 853rd 823126 846 63 14ms 14 Nov 2024 853rd Palladium02 846 63 9ms 12 May 2025 853rd 4very 846 63 10ms 10 Jun 2025 853rd Ultra814 846 63 9ms 21 Aug 2025 865th NewDefectus 🇮🇱 846 73 3ms 6 May 2022 865th inventshah 846 73 2ms 12 Jun 2022 865th Natanaelel 🇸🇪 846 73 3ms 15 Jun 2022 865th Herbert00709 🇵🇱 846 73 2ms 22 Dec 2023 865th LorenzoDeGaspari 846 73 2ms 27 May 2024 865th Bpc-CPU 846 73 2ms 12 Jul 2025 865th AZTECCO 846 73 2ms 16 Sep 2025 865th CaedenHarper 🇨🇦 846 73 2ms 28 Sep 2025 865th prestosilver 🇺🇸 846 73 2ms 26 days ago 874th DialFrost 🇸🇬 846 87 42ms 14 days ago 875th jared-hughes 846 100 63ms 20 Jul 2022 875th ZakkkkAttackkkk 🇵🇭 846 100 64ms 10 Aug 2022 875th Walter225 846 100 63ms 25 Jul 2023 878th Natanaelel 🇸🇪 845 57 417ms 17 Jan 2024 878th Kacarott 🇦🇺 845 57 394ms 10 Sep 2024 878th albanian-laundromat 845 57 494ms 7 Oct 2025 First Prev 801–880 of 3,488 Next Last