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Square root of 17

√17 ≈ 4.1231. The square root of 17 is about 4.1231. 17 is not a perfect square, so √17 is irrational: its decimals never end or repeat.

√17 at a glance.
Value4.12310563
Rounded4.1 (1 dp) · 4.12 (2 dp) · 4.123 (3 dp)
Simplest radical form√17
Perfect square?No — between 4² = 16 and 5² = 25
17 squared289

Estimating √17 in your head

Start from the nearest perfect square, 4² = 16. 17 is 1 more than that. Divide the difference by twice the root, 8, and add it:

√17 ≈ 4 + 1 ÷ 8 ≈ 4.125

The true value is 4.1231, so the one-step estimate is off by about 0.002. The estimate always comes out slightly high, and it is closest when 17 is near a perfect square. The method is explained in estimating square roots in your head.

Can √17 be simplified?

No. 17 has no perfect-square factor besides 1, so √17 is already in simplest radical form.

Frequently asked questions

What is the square root of 17?

The square root of 17 is about 4.1231. 17 is not a perfect square, so √17 is irrational: its decimals never end or repeat.

Is 17 a perfect square?

No. It lies between 4² = 16 and 5² = 25.

What is √17 in simplest radical form?

√17 is already in simplest form: 17 has no square factor other than 1.

Practise estimating square roots

Nearby: √16 · √18 · all square roots to 150