The MATH+ Advent calendar problems will be released daily from 1 to 24 December:
Challenge 1
Challenge 2
Challenge 3
Challenge 4
Challenge 5
Challenge 6
Challenge 7
Challenge 8
Challenge 9
Challenge 10
Challenge 11
Challenge 12
Challenge 13
Challenge 14
Challenge 15
Challenge 16
Challenge 17
Challenge 18
Challenge 19
Challenge 20
Challenge 21
Challenge 22
Challenge 23
Challenge 24
The list of answers to the 2021 challenges can be found here. Detailed solutions will be published soon.