| 1049 | Brave Balloonists | USU Local Contest. March 2000 | 5390 | 238 |
| 1086 | Cryptography | Spring School Contest 2001 | 10332 | 112 |
| 1091 | Tmutarakan Exams | USU Local Contest. March 2001 | 2217 | 495 |
| 1104 | Don’t Ask Woman about Her Age | Tetrahedron Team Online Contest May 2001 | 4477 | 95 |
| 1118 | Nontrivial Numbers | Autumn School Contest 2001 | 4367 | 98 |
| 1133 | Fibonacci Sequence | NEERC 2001 Central Subregional | 2313 | 184 |
| 1204 | Idempotents | USU Local Contest. March 2002 | 1872 | 229 |
| 1261 | Tips | Autumn School Contest 2003 | 1271 | 345 |
| 1286 | Starship Travel | USU Personal Contest 2004 | 642 | 681 |
| 1352 | Mersenne Primes | Spring School Contest 2005 | 3412 | 132 |
| 1355 | Bald Spot Revisited | Spring School Contest 2005 | 1989 | 225 |
| 1356 | Something Easier | Spring School Contest 2005 | 1252 | 357 |
| 1430 | Crime and Punishment | Timus Top Coders: First Challenge | 927 | 468 |
| 1456 | Jedi Riddle 2 | Timus Top Coders: Second Challenge | 548 | 771 |
| 1554 | Multiplicative Functions | Petrozavodsk Summer 2007. NSU Contest | 590 | 623 |
| 1560 | Elementary Symmetric Functions | Petrozavodsk Summer 2007. NSU Contest | 371 | 980 |
| 1698 | Square Country 5 | Petrozavodsk Winter 2009. USU Contest | 538 | 583 |
| 1748 | The Most Complex Number | Petrozavodsk Summer 2009. Ufa SATU Contest | 1085 | 265 |
| 1807 | Cartridges for Maxim | NEERC 2010 Eastern Subregional | 193 | 1304 |
| 2070 | Interesting Numbers | Ural Regional School Programming Contest 2015 | 596 | 195 |
| 2102 | Michael and Cryptography | Ural FU Junior Championship 2016 | 750 | 117 |
