Square Root of 36

The square root of 36 is exactly 6, because 6 × 6 = 36. The negative number −6 squares to 36 too.

Whole numbers, decimals or fractions like 9/16. Negative numbers have no real root.
Decimal
6
Both real square roots
±6x² = 36 has two real solutions
Perfect power?
Yes
√366

Show the work

  1. 36 is a perfect square: 62 = 36.
  2. So √36 = 6.

√36 at a glance

Exact value
6
Decimal (10 places)
6
Rounded
6
Perfect square?
Yes — 6²
Rational?
Rational (whole number)
Both square roots
±6
Prime factorization
2² × 3²
Cube root
3.301927

How to simplify √36

Write 36 as a product of primes and halve every exponent. Because each exponent is even, nothing is left under the radical sign:

36 = 2² × 3²
√36 = 2 × 3 = 6

36 has 5 factor pairs (1 × 36, 2 × 18, 3 × 12, 4 × 9, 6 × 6). The pair with two equal numbers, 6 × 6, is what makes it a perfect square — and why it has an odd number of factors.

Every perfect square is also a sum of consecutive odd numbers starting at 1. Here 36 = 1 + 3 + 5 + 7 + … + 11, the first 6 odd numbers.

Where √36 sits between perfect squares

36 is 6². The perfect squares on either side are 25 (5²) and 49 (7²), so the gaps are 11 below and 13 above — consecutive squares always differ by consecutive odd numbers.

55² = 2566² = 3677² = 49√36 = 6
√36 on a number line, with tenths marked between 5 and 7.

Finding √36 with the Babylonian method

Picture a rectangle with an area of 36 and one side x; the other side must be 36 ÷ x. Averaging the two sides gives a rectangle that is closer to a square, and the side of that square is exactly √36.

xnext = (x + 36 ÷ x) ÷ 2

To show the method at work on a perfect square, start one above the answer, at 7:

StepGuess x36 ÷ xAverageCorrect decimals
17.00000000005.14285714296.07142857141
26.07142857145.92941176476.00042016813
36.00042016815.99957986146.00000001477
46.00000001475.99999998536.0000000000all 10 shown

The count of correct decimals went 1, 3, 7 and all 10 over 4 steps — roughly doubling each time — until the guess matched √36 = 6.0000000000 to every decimal shown.

√36 in geometry and everyday measurements

  • A square room or garden bed covering 36 square feet measures exactly 6 ft (6 ft) along each wall.
  • 36 is not a sum of two whole-number squares — no pair of squares adds up to it — so √36 is never the diagonal of a rectangle with whole-number sides. It is, however, the space diagonal of a 2 × 4 × 4 box, because 2² + 4² + 4² = 36.
RootSimplest formDecimalPerfect square?
√33√335.7446No
√34√345.8310No
√35√355.9161No
√3666.0000Yes
√37√376.0828No
√38√386.1644No
√39√396.2450No
  • The cube root of 36 is about 3.301927.
  • Taking the square root twice gives the fourth root: √6 ≈ 2.449490.
  • Four times the radicand doubles the root: √144 = 2 × √36 ≈ 12.

Frequently asked questions

What is the square root of 36?

The square root of 36 is 6, because 6 × 6 = 36. Strictly, 36 has two square roots, 6 and −6; the √ symbol means the positive one.

Is the square root of 36 rational or irrational?

Rational. 36 is a perfect square, so its square root is the whole number 6.

Can √36 be simplified?

Yes, all the way to a whole number: √36 = 6.

What is √36 rounded to two decimal places?

√36 is exactly 6, or 6.00 written to two decimal places.

Need a different value? Use the Square root calculator, or browse the Square roots 1–1,000.