nth Root Calculator

The nth root calculator finds the principal root of any number for any root index you choose. A root is the inverse of exponentiation: the nth root of a number x is the value that, when multiplied by itself n times, gives back x. The square root is the 2nd root, the cube root is the 3rd root, and you can go as high as you like with 4th, 5th, or higher roots. The formula is straightforward: the nth root of x equals x raised to the power of one over n, written as x^(1/n). You enter two values: the root index n (which must be a positive integer) and the radicand, which is the number you want to find the root of. The calculator returns the principal root rounded to six decimal places, a verification figure showing what happens when you raise the result back to the power n (which should match your original radicand), and a written description of the operation. For odd-indexed roots of negative numbers, the real root exists and is negative. For even-indexed roots of negative numbers, the result is complex and the calculator will tell you so rather than returning an error silently. The tool is useful for students working through algebra, calculus, or physics problems, for engineers converting between power laws, and for anyone who needs a fast, reliable check of a root calculation. Results are mathematical values and carry no rounding guarantee beyond six decimal places.

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5
3rd root of 125
Verification (result^n)125
Root as exponent125^(1/3)
Decimal places6

How it works

The calculator evaluates the nth root using the standard relationship: the nth root of x equals x raised to the power 1/n. In JavaScript this is computed as Math.pow(Math.abs(x), 1/n), with the sign of the result set to negative when x is negative and n is an odd integer. For even root indices and a negative radicand, the principal real root does not exist, so the calculator displays a note instead of a number. The verification step raises the result back to the power n to confirm it equals the original radicand, giving you a built-in accuracy check. Rounding to six decimal places keeps the output readable without hiding the precision of the calculation.

Worked example

Using the default values, n is 3 and the radicand is 125. The cube root of 125 is 125^(1/3) = 5. Verification: 5 cubed is 5 x 5 x 5 = 125, which matches. For a second check, try n = 4 and radicand = 256: the 4th root is 256^(1/4) = 4, and 4 to the 4th power is 256.

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