12 Days of Christmas
9th
Arabic to Roman
6th
Christmas Trees
7th
Diamonds
5th
Divisors
1st
Emirp Numbers
14th
Evil Numbers
27th
Fibonacci
1st
Leap Years
8th
Niven Numbers
32nd
Ordinal Numbers
12th
Pangram Grep
Pascal’s Triangle
7th
Pernicious Numbers
36th
Prime Numbers
31st
Quine
24th
Roman to Arabic
12th
Sierpiński Triangle
16th