Curated
4| # | Title | Difficulty | Source | Tags | |
|---|---|---|---|---|---|
| 3 | A sum that's never wholeDivisibility | Deep | Lemma | ||
| 37 | Zeros at the end of 100!Factorials | Deep | Lemma | ||
| 62 | The last two digits of a giantPatterns | Deep | Lemma | ||
| 1132 | Repeating‑digit divisorDivisibility | Deep | Hall & Knight |
From open sources
4Complete problems only, with worked solutions first. Show everything
| # | Title | Difficulty | |
|---|---|---|---|
| 10817 | Matt needs to buy new plates for his home | Deep | |
| 11804 | There are 90 students who have lunch during period 5 | Deep | |
| 13325 | Monica and Sheila are twins | Deep | |
| 15020 | Sienna gave Bailey half of her suckers | Deep |