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Nth Root Calculator

Nth root calculator computes square roots, cube roots, 4th roots, and any root of a number. The 4th root of 81 = 3 because 3^4 = 81. Supports odd roots of negative numbers like the cube root of -27 = -3.

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Formula

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Core Formula
xn=x1n\sqrt[n]{x} = x^{\frac{1}{n}}

How it works: The nth root of a number is the value raised to the power 1/n. For example, the cube root of 27 = 27^(1/3) = 3.

Worked Example

Find the 4th root of 81.
1Step 1: We need x where x^4 = 81.
2Step 2: 81^(1/4) = (3^4)^(1/4) = 3. Verify: 3 x 3 x 3 x 3 = 81. More examples: square root of 144 = 144^(1/2) = 12, cube root of 125 = 125^(1/3) = 5, 5th root of 32 = 32^(1/5) = 2, cube root of -27 = -3 (odd roots of negatives are real).

What is an Nth Root?

The nth root of a number x is the value that, when multiplied by itself n times, equals x. It is written as x^(1/n) or the radical symbol with index n.

  • Square root (n=2): sqrt(x) is the most common root. sqrt(25) = 5 because 5 x 5 = 25
  • Cube root (n=3): cbrt(x) finds the value cubed to get x. cbrt(27) = 3 because 3 x 3 x 3 = 27
  • Odd roots of negative numbers are real: cbrt(-8) = -2 because (-2)^3 = -8
  • Even roots of negative numbers have no real solution: there is no real number whose square is -4

Nth roots are used in geometry (finding side lengths from volumes or areas), finance (calculating compound growth rates), and science (dimensional analysis).

You can also calculate changes using our Scientific Calculator or Factorial Calculator.

Frequently Asked Questions

What is the 4th root of 81?

The 4th root of 81 is 3, because 3^4 = 3 x 3 x 3 x 3 = 81. You can also compute this as 81^(1/4) = 81^0.25 = 3.

Can I take the square root of a negative number?

Not in the real numbers. Even roots (2nd, 4th, 6th) of negative numbers have no real solution because no real number multiplied by itself an even number of times produces a negative result. However, odd roots of negatives are valid: the cube root of -27 = -3.

What is the difference between a square root and a cube root?

A square root finds what number times itself equals x (sqrt(9) = 3 because 3 x 3 = 9). A cube root finds what number times itself three times equals x (cbrt(27) = 3 because 3 x 3 x 3 = 27). Higher roots work the same way with more multiplications.

How do I calculate nth root without a calculator?

For perfect roots, factor the number: 81 = 3^4, so the 4th root is 3. For non-perfect roots, use estimation: the cube root of 50 is between 3 (3^3=27) and 4 (4^3=64), closer to 3.68. For precise values, use the formula x^(1/n) on any calculator.

Where are nth roots used in real life?

Square roots appear in distance formulas (Pythagorean theorem), physics (kinetic energy), and statistics (standard deviation). Cube roots are used for finding dimensions of cubic volumes. In finance, nth roots calculate compound annual growth rate: CAGR = (final/initial)^(1/years) - 1.

How can I put this Nth Root Calculator on my blog or website?

Yes, the Nth Root Calculator is fully embeddable. Tap "Embed" above to configure appearance and copy the code. It is free to use, works on any platform (HTML, WordPress, CMS), and adjusts to any screen size automatically. Visit calculory.com/services/embed-calculators for the complete guide.

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