| Problem Name | Online Judge | Year | Contest | Difficulty Level | |
|---|---|---|---|---|---|
| 1 | LCM Sum | SPOJ | 1 | ||
| 2 | Panoramix's Prediction | Codeforces | Codeforces Beta Round #69 (Div. 2 Only) | 1 | |
| 3 | Coprime Triples | CodeChef | 1 | ||
| 4 | GCD Extreme | SPOJ | 1 | ||
| 5 | Sky Code | Live Archive | 2008 | Europe - Southeastern | 2 |
| 6 | Expected Greatest Common Divisor | CodeChef | 3 | ||
| 7 | Adding Least Common Multiples | CodeChef | 5 | ||
| 8 | Unusual Sequences | Codeforces | Codeforces Round #450 (Div. 2) | 6 | |
| 9 | Mobius Multiplications | CodeChef | 7 | ||
| 10 | GCD Extreme (hard) | SPOJ | 7 |