12 Days of Christmas
8th
99 Bottles of Beer
6th
Abundant Numbers
26th
Christmas Trees
5th
CSS Colors
5th
Diamonds
5th
Divisors
11th
Emirp Numbers
Fibonacci
44th
Fizz Buzz
28th494th1,437th
Happy Numbers
31st
Intersection
3rd
Leap Years
13th
Morse Decoder
3rd
Morse Encoder
4th
Niven Numbers
30th
Prime Numbers
33rd
Seven Segment
5th
Sierpiński Triangle
11th
Tongue-twisters
17th
United States
7th