Square root of 129
√129 ≈ 11.3578. The square root of 129 is about 11.3578. 129 is not a perfect square, so √129 is irrational: its decimals never end or repeat.
| Value | 11.35781669 |
|---|---|
| Rounded | 11.4 (1 dp) · 11.36 (2 dp) · 11.358 (3 dp) |
| Simplest radical form | √129 |
| Perfect square? | No — between 11² = 121 and 12² = 144 |
| 129 squared | 16,641 |
Estimating √129 in your head
Start from the nearest perfect square, 11² = 121. 129 is 8 more than that. Divide the difference by twice the root, 22, and add it:
√129 ≈ 11 + 8 ÷ 22 ≈ 11.364
The true value is 11.3578, so the one-step estimate is off by about 0.006. The estimate always comes out slightly high, and it is closest when 129 is near a perfect square. The method is explained in estimating square roots in your head.
Can √129 be simplified?
No. 129 has no perfect-square factor besides 1, so √129 is already in simplest radical form.
Frequently asked questions
What is the square root of 129?
The square root of 129 is about 11.3578. 129 is not a perfect square, so √129 is irrational: its decimals never end or repeat.
Is 129 a perfect square?
No. It lies between 11² = 121 and 12² = 144.
What is √129 in simplest radical form?
√129 is already in simplest form: 129 has no square factor other than 1.
Practise estimating square rootsNearby: √128 · √130 · all square roots to 150