12 Days of Christmas
40th
24 Game
11th
99 Bottles of Beer
26th
Arrows
21st
Card Number Validation
15th
Collatz
31st
Day of Week
25th
Diamonds
29th
Divisors
133rd
Farey Sequence
19th
Fizz Buzz
259th
Forsyth–Edwards Notation
11th
ISBN
31st
Kaprekar Numbers
12th
Leap Years
78th
Niven Numbers
61st
Pernicious Numbers
51st
Rock-paper-scissors-Spock-lizard
10th
Seven Segment
32nd
Ten-pin Bowling
8th
Tongue-twisters
21st
π
18th
𝑒
21st