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Exponent and Root Calculator (Power, Square Root, Cube Root, n-th Root)

Raise a number to any power (including fractional and negative exponents) and take its square root, cube root and n-th root.

Version 2

Things to keep in mind:

  • Complex results (e.g. √−4 = 2i) are not computed; 0 and "real = 0" are shown instead.
  • Very small results (e.g. 10⁻²⁰) are rounded to 8 decimals and may show as 0.00000000.
  • Base ±1,000,000, exponent ±1,000, radicand ±10¹² and root index 1–100.

Calculator

Power (xʸ)

The number to raise; may be negative (a negative base needs a whole-number exponent).

The power; may be fractional or negative (x^0.5 = √x, x^−1 = 1/x).

Root (ⁿ√a)

The square root, cube root and n-th root are taken of this number.

Between 1 and 100; 2 is the square root, 3 the cube root. A negative number has a real root only for an odd whole n.

After the first calculation, the result updates automatically when you change a value.

Result

Enter the values and press Calculate to see the result here.

About this tool

The tool has two parts: powers (xʸ) and roots (ⁿ√a). Powers work with whole, fractional and negative exponents; the root part returns the square root, the cube root and the n-th root you choose for the same number.

Rules and formulas

  • xʸ: for a whole y, x multiplied by itself y times; x⁰ = 1, x⁻ʸ = 1 / xʸ
  • A fractional exponent is a root: x^(1/n) = ⁿ√x, x^(m/n) = (ⁿ√x)ᵐ
  • ⁿ√a = a^(1/n); √a = a^(1/2), ∛a = a^(1/3)
  • A negative a has a real root only for an odd whole n: ⁿ√a = −ⁿ√|a| (e.g. the fifth root of −32 is −2)
  • A negative base is raised only to whole exponents: (−2)³ = −8, but (−8)^0.5 is not a real number

Example: 2¹⁰ = 1024; the cube root of 27 is 3 and its square root √27 ≈ 5.19615242. 1.5⁻² = 1 / 2.25 ≈ 0.44444444.

Undefined cases (a negative base with a fractional exponent, zero to a negative power, an even root of a negative number) are reported as 0 with the "computed = 0" flag instead of an error. Powers above roughly 10²⁹ are not computed either.

Extra example: 1000^0.4 ≈ 15.84893192. The fifth root of −32 is −2; the cube root of the same number is ≈ −3.17480210, while its square root is not real and shows 0.

How to read the result: check the “Power computed” and “n-th root is real” flags first: 1 means the result is valid, 0 means it is undefined or not a real number and the related value is shown as 0. Results are rounded to 8 decimals; irrational values (such as √27) are approximations. The cube root is always real for negative numbers; the square root and other even roots are computed only for non-negative numbers.

How to use

  1. In the power part enter the base (x) and the exponent (y).
  2. In the root part enter the radicand (a) and the root index (n).
  3. Press Calculate; the power, n-th root, square root and cube root are shown together.

Notes

Arithmetic uses 64 significant digits and results are rounded to 8 decimals (HALF_UP), so irrational results such as √2 are approximations. 0⁰ is taken as 1. A power is not computed when |y × ln|x|| exceeds 66.775 (about 10²⁹). The n-th root of a negative number is returned as −ⁿ√|a| only when n is an odd whole number (3, 5, 7 …); the cube root of a negative number is always real.

Frequently asked questions

4 questions
  1. It is the power of the reciprocal: x⁻ʸ = 1 / xʸ. For example 2⁻³ = 1/8 = 0.125 and 1.5⁻² ≈ 0.44444444.

Next step

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