√15 ≈ 3.8730
√15 is an irrational number, so its decimals never end or repeat. It sits between 3 and 4 because 3² = 9 and 4² = 16.
| Decimal places | Value |
|---|---|
| 0 | 4 |
| 1 | 3.9 |
| 2 | 3.87 |
| 3 | 3.873 |
| 4 | 3.8730 |
| 5 | 3.87298 |
| 10 (digits) | 3.8729833462 |
15 has no perfect-square factor other than 1, so √15 is already in simplest radical form.
3.8730 × 3.8730 ≈ 15.0001, which is very close to 15.
Need another number? Use the square root calculator (also cube roots and other roots).
| Number | Square root |
|---|---|
| 11 | 3.3166 |
| 12 | 3.4641 |
| 13 | 3.6056 |
| 14 | 3.7417 |
| 16 | 4 |
| 17 | 4.1231 |
| 18 | 4.2426 |
| 19 | 4.3589 |