√166 ≈ 12.8841
√166 is an irrational number, so its decimals never end or repeat. It sits between 12 and 13 because 12² = 144 and 13² = 169.
| Decimal places | Value |
|---|---|
| 0 | 13 |
| 1 | 12.9 |
| 2 | 12.88 |
| 3 | 12.884 |
| 4 | 12.8841 |
| 5 | 12.88410 |
| 10 (digits) | 12.8840987267 |
166 has no perfect-square factor other than 1, so √166 is already in simplest radical form.
12.8841 × 12.8841 ≈ 166.0000, which is very close to 166.
Need another number? Use the square root calculator (also cube roots and other roots).
| Number | Square root |
|---|---|
| 162 | 12.7279 |
| 163 | 12.7671 |
| 164 | 12.8062 |
| 165 | 12.8452 |
| 167 | 12.9228 |
| 168 | 12.9615 |
| 169 | 13 |
| 170 | 13.0384 |