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Square root of 13

√13 ≈ 3.6056. The square root of 13 is about 3.6056. 13 is not a perfect square, so √13 is irrational: its decimals never end or repeat.

√13 at a glance.
Value3.60555128
Rounded3.6 (1 dp) · 3.61 (2 dp) · 3.606 (3 dp)
Simplest radical form√13
Perfect square?No — between 3² = 9 and 4² = 16
13 squared169

Estimating √13 in your head

Start from the nearest perfect square, 4² = 16. 13 is 3 less than that. Divide the difference by twice the root, 8, and subtract it:

√13 ≈ 4 − 3 ÷ 8 ≈ 3.625

The true value is 3.6056, so the one-step estimate is off by about 0.019. The estimate always comes out slightly high, and it is closest when 13 is near a perfect square. The method is explained in estimating square roots in your head.

Can √13 be simplified?

No. 13 has no perfect-square factor besides 1, so √13 is already in simplest radical form.

Frequently asked questions

What is the square root of 13?

The square root of 13 is about 3.6056. 13 is not a perfect square, so √13 is irrational: its decimals never end or repeat.

Is 13 a perfect square?

No. It lies between 3² = 9 and 4² = 16.

What is √13 in simplest radical form?

√13 is already in simplest form: 13 has no square factor other than 1.

Practise estimating square roots

Nearby: √12 · √14 · all square roots to 150