| 1049 | Brave Balloonists | USU Local Contest. March 2000 | 5308 | 237 |
| 1086 | Cryptography | Spring School Contest 2001 | 9912 | 114 |
| 1091 | Tmutarakan Exams | USU Local Contest. March 2001 | 2181 | 492 |
| 1104 | Don’t Ask Woman about Her Age | Tetrahedron Team Online Contest May 2001 | 4349 | 95 |
| 1118 | Nontrivial Numbers | Autumn School Contest 2001 | 4179 | 100 |
| 1133 | Fibonacci Sequence | NEERC 2001 Central Subregional | 2257 | 185 |
| 1204 | Idempotents | USU Local Contest. March 2002 | 1827 | 229 |
| 1261 | Tips | Autumn School Contest 2003 | 1237 | 347 |
| 1286 | Starship Travel | USU Personal Contest 2004 | 629 | 681 |
| 1352 | Mersenne Primes | Spring School Contest 2005 | 3308 | 133 |
| 1355 | Bald Spot Revisited | Spring School Contest 2005 | 1913 | 230 |
| 1356 | Something Easier | Spring School Contest 2005 | 1221 | 359 |
| 1430 | Crime and Punishment | Timus Top Coders: First Challenge | 900 | 472 |
| 1456 | Jedi Riddle 2 | Timus Top Coders: Second Challenge | 532 | 777 |
| 1554 | Multiplicative Functions | Petrozavodsk Summer 2007. NSU Contest | 578 | 619 |
| 1560 | Elementary Symmetric Functions | Petrozavodsk Summer 2007. NSU Contest | 359 | 986 |
| 1698 | Square Country 5 | Petrozavodsk Winter 2009. USU Contest | 522 | 581 |
| 1748 | The Most Complex Number | Petrozavodsk Summer 2009. Ufa SATU Contest | 1021 | 271 |
| 1807 | Cartridges for Maxim | NEERC 2010 Eastern Subregional | 186 | 1292 |
| 2070 | Interesting Numbers | Ural Regional School Programming Contest 2015 | 516 | 199 |
| 2102 | Michael and Cryptography | Ural FU Junior Championship 2016 | 598 | 123 |
