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Square root of 12

√12 ≈ 3.4641. The square root of 12 is about 3.4641, which simplifies to 2√3. 12 is not a perfect square, so √12 is irrational: its decimals never end or repeat.

√12 at a glance.
Value3.46410162
Rounded3.5 (1 dp) · 3.46 (2 dp) · 3.464 (3 dp)
Simplest radical form2√3
Perfect square?No — between 3² = 9 and 4² = 16
12 squared144

Estimating √12 in your head

Start from the nearest perfect square, 3² = 9. 12 is 3 more than that. Divide the difference by twice the root, 6, and add it:

√12 ≈ 3 + 3 ÷ 6 ≈ 3.5

The true value is 3.4641, so the one-step estimate is off by about 0.036. The estimate always comes out slightly high, and it is closest when 12 is near a perfect square. The method is explained in estimating square roots in your head.

Simplifying √12

Find the largest perfect square that divides 12: it is 4, since 12 = 4 × 3. Take its root outside: √12 = √4 × √3 = 2√3.

Frequently asked questions

What is the square root of 12?

The square root of 12 is about 3.4641, which simplifies to 2√3. 12 is not a perfect square, so √12 is irrational: its decimals never end or repeat.

Is 12 a perfect square?

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

What is √12 in simplest radical form?

√12 = √(4 × 3) = 2√3.

Practise estimating square roots

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