12 Days of Christmas
23rd
99 Bottles of Beer
33rd
Abundant Numbers
17th
Arabic to Roman
24th
Christmas Trees
10th
Divisors
19th
Emirp Numbers
20th
Evil Numbers
49th
Fibonacci
1st
Fizz Buzz
43rd
Foo Fizz Buzz Bar
16th
Happy Numbers
48th
Leap Years
20th
Niven Numbers
30th
Odious Numbers
46th
Ordinal Numbers
19th
Pangram Grep
8th
Pascal’s Triangle
32nd
Pernicious Numbers
37th
Prime Numbers
41st
Roman to Arabic
13th
Seven Segment
17th
Spelling Numbers
United States
23rd
λ
13th
π
25th
τ
18th
φ
32nd
√2
38th
𝑒
25th