| 1049 | Brave Balloonists | USU Local Contest. March 2000 | 5197 | 237 |
| 1086 | Cryptography | Spring School Contest 2001 | 9544 | 116 |
| 1091 | Tmutarakan Exams | USU Local Contest. March 2001 | 2151 | 489 |
| 1104 | Don’t Ask Woman about Her Age | Tetrahedron Team Online Contest May 2001 | 4220 | 96 |
| 1118 | Nontrivial Numbers | Autumn School Contest 2001 | 4025 | 101 |
| 1133 | Fibonacci Sequence | NEERC 2001 Central Subregional | 2205 | 185 |
| 1204 | Idempotents | USU Local Contest. March 2002 | 1781 | 230 |
| 1261 | Tips | Autumn School Contest 2003 | 1201 | 350 |
| 1286 | Starship Travel | USU Personal Contest 2004 | 622 | 675 |
| 1352 | Mersenne Primes | Spring School Contest 2005 | 3225 | 134 |
| 1355 | Bald Spot Revisited | Spring School Contest 2005 | 1858 | 232 |
| 1356 | Something Easier | Spring School Contest 2005 | 1177 | 365 |
| 1430 | Crime and Punishment | Timus Top Coders: First Challenge | 870 | 478 |
| 1456 | Jedi Riddle 2 | Timus Top Coders: Second Challenge | 513 | 789 |
| 1554 | Multiplicative Functions | Petrozavodsk Summer 2007. NSU Contest | 564 | 617 |
| 1560 | Elementary Symmetric Functions | Petrozavodsk Summer 2007. NSU Contest | 351 | 981 |
| 1698 | Square Country 5 | Petrozavodsk Winter 2009. USU Contest | 509 | 576 |
| 1748 | The Most Complex Number | Petrozavodsk Summer 2009. Ufa SATU Contest | 980 | 271 |
| 1807 | Cartridges for Maxim | NEERC 2010 Eastern Subregional | 180 | 1275 |
| 2070 | Interesting Numbers | Ural Regional School Programming Contest 2015 | 443 | 201 |
| 2102 | Michael and Cryptography | Ural FU Junior Championship 2016 | 472 | 127 |
