12 Days of Christmas
10th
99 Bottles of Beer
7th
Abundant Numbers
29th
Christmas Trees
5th
CSS Colors
5th
Diamonds
5th
Divisors
13th
Emirp Numbers
Fibonacci
46th
Fizz Buzz
28th506th1,476th
Happy Numbers
33rd
Intersection
4th
Leap Years
14th
Morse Decoder
3rd
Morse Encoder
4th
Niven Numbers
33rd
Prime Numbers
34th
Seven Segment
5th
Sierpiński Triangle
12th
Tongue-twisters
17th
United States
7th