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Root Calculator

Last updated: June 2026

Square Root Calculator

=
5.196152
27
5.196152
Exact (fraction)
27^(1/2)
Squared back
27.000000
Is perfect square?
✗ No
Reciprocal (1/√a)
0.192450

Cube Root Calculator

=
3.000000
27
3.000000
Exact (fraction)
27^(1/3)
Cubed back
27.000000
Is perfect cube?
✓ Yes
As exponent
27^0.333…

General Root Calculator — ⁿ√a

8√15
1.402851
As exponent
15^(1/8)
Result^8 (verify)
15.000000
Decimal exponent
0.125000
Newton's Method — Estimation Steps for 8√15
StepGuess (b)a ÷ b^(n-1)New Average
11.3332.0057661.417096
21.4170961.3070641.403342
31.4033421.3994171.402851
Formula each step: new = [b × (n−1) + c] / n where c = a ÷ bn−1. Repeat until converged.

Square Root & Cube Root Reference Table

n√(n²)∛(n³)
11111
24282
393273
4164644
52551255
63662166
74973437
86485128
98197299
1010010100010
1112111133111
1214412172812

About Roots & Estimation

The nth root of a number a is a number b such that bⁿ = a. The square root (n=2) and cube root (n=3) are the most common. Roots can be written as ⁿ√a = a^(1/n).

Estimating √a (Babylonian Method)
  1. Guess a number b
  2. Compute c = a ÷ b
  3. If c is precise enough, stop
  4. New guess = (b + c) ÷ 2
  5. Repeat from step 2
Estimating ⁿ√a (nth Root)
  1. Guess a number b
  2. Compute c = a ÷ b^(n−1)
  3. If c is precise enough, stop
  4. New guess = [b×(n−1) + c] ÷ n
  5. Repeat from step 2
EX: √27 to 3 decimal placesGuess: 5.125
27 ÷ 5.125 = 5.268
(5.125 + 5.268)/2 = 5.197
27 ÷ 5.197 = 5.195
(5.195 + 5.197)/2 = 5.196
27 ÷ 5.196 ≈ 5.196 ✓
EX: ⁸√15 to 3 decimal placesGuess: 1.432
15 ÷ 1.432⁷ = 1.405
(1.432×7 + 1.405)/8 = 1.388
15 ÷ 1.388⁷ = 1.403
(1.403×7 + 1.388)/8 = 1.402
Converges → 1.403
Even root of negative
Not a real number (NaN)
√−4 has no real solution
Odd root of negative
Negative result
∛−8 = −2 (since (−2)³ = −8)
Root as exponent
ⁿ√a = a^(1/n)
⁴√81 = 81^0.25 = 3
Nested roots
√(√a) = a^(1/4)
√(√16) = 16^0.25 = 2

Calculate square roots, cube roots, and any nth root. Includes Newton's method step-by-step estimation and a perfect square reference table.

The Root Calculator is a mathematical utility designed to find the roots of numbers, including square roots, cube roots, and higher nth roots. In algebra, finding the root of a number is the inverse operation of raising a number to a power. The nth root of a value x is a number y which, when multiplied by itself n times, equals x (y^n = x). Roots are essential in physics, construction, and engineering.

The square root (where n = 2) is the most common root calculation. For example, the square root of 25 is 5, because 5 * 5 = 25. While perfect squares yield integers, most numbers have irrational roots that continue infinitely without repeating (e.g., the square root of 2 is approximately 1.414213). The root calculator uses advanced numerical methods, such as Newton's approximation method, to calculate these irrational roots with high precision.

A cube root (where n = 3) calculates a number that, when multiplied by itself three times, yields the base (e.g., the cube root of 27 is 3, since 3 * 3 * 3 = 27). Higher nth roots are written using radical notation or as fractional exponents, where the nth root of x is equivalent to x^(1/n). For example, the 4th root of 81 is 81^(1/4) = 3.

Roots are used in geometry to compute dimensions of shapes. For instance, the length of the side of a square is the square root of its area. In statistics, the standard deviation is the square root of the variance. In electrical engineering, root mean square (RMS) values are calculated to measure the effective voltage of alternating current (AC) electricity.

By automating these complex calculations, the root calculator provides fast and accurate answers for students and professionals alike. It eliminates the need for manual estimation or trial-and-error methods, making it a valuable tool for algebraic homework, structural engineering designs, and physics calculations.

How it Works & Formula

ⁿ√a = b ↔ bⁿ = a

The nth root of a number a is another number b such that b raised to the power n equals a. The square root uses n=2, cube root uses n=3.

Practical Examples

Example 1: Cube Root of 27

³√27 = 3, because 3 × 3 × 3 = 27.

Frequently Asked Questions

Can you take a root of a negative number?

Yes, if the degree of the root (n) is odd (e.g., ³√-8 = -2). Even roots of negative numbers result in complex numbers.