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mathClassic tool

Root Calculator

Calculate square roots, cube roots, and custom nth roots with instant results, power checks, and correct handling for negative numbers with odd indices.

Use this root calculator to solve square roots, cube roots, and custom nth roots in seconds. Enter a number, choose the root type, and adjust decimal precision when you need a cleaner approximation.

The tool also shows the formula used, checks the inverse power, and labels the answer as exact or approximate. That makes it useful for algebra homework, exam review, engineering notes, and quick mental-math confirmation.

When the input is negative, the calculator accepts valid odd-index roots and blocks impossible even-index cases. This keeps the result grounded in real numbers and avoids common interpretation mistakes.

Enter a number and choose the root type to calculate it instantly.

Result

Fill in the fields to calculate the root.

Summary —

Index used —

Formula —

Root value —

Power check —

Result type —

Use clear inputs to get a more useful result.

How to use the root calculator

Type the number you want to evaluate, choose square, cube, or custom nth root, and update the form to see the result. For a custom root, enter a positive whole-number index.

When is a negative number valid?

Odd roots can return real values for negative numbers, such as the cube root of -125. Even roots such as square root or fourth root do not produce a real result for a negative radicand.

Quick examples

  • √81 = 9
  • ∛125 = 5
  • 4√16 = 2