√400 = 20
400 is a perfect square: 20 × 20 = 400, so √400 = 20 exactly (no decimals).
Need another number? Use the square root calculator (also cube roots and other roots).
| Number | Square root |
|---|---|
| 250 | 15.8114 |
| 256 | 16 |
| 300 | 17.3205 |
| 324 | 18 |
| 500 | 22.3607 |
| 529 | 23 |
| 625 | 25 |
| 900 | 30 |