Find the principal, non-negative square root of a positive number or zero. The calculator also displays a multiplication check.
The principal square root √a is the non-negative number r for which r² = a.
√144 = 12 because 12 × 12 = 144. √2 ≈ 1.414214. Although the equation x² = 144 has roots +12 and −12, the principal square root is 12.
Negative inputs have no real square root and are rejected. Irrational results are rounded, so squaring the displayed approximation may not reproduce every digit of the original input.
Editorial responsibility: Nicolas Belotti · Methods and testing · Report an error
English edition: 16 September 2026.