√20 =
2√5
≈ 4.472136
Square root of 20 — 4.472136 (2√5)
Irrational
The square root of 20 is about 4.472136, or exactly 2√5. It lies between 4 and 5.
- As a decimal
- ≈ 4.472136
- Simplified surd
- √20 = 2√5
- Between
- 4 < √20 < 5
- Squared
- 20² = 400
- Cube root
- ∛20 ≈ 2.714418
How the surd is simplified
Pull out the largest square factor. Since 50 = 25 × 2, the root of 25 comes out as 5 and the 2 stays behind: 5√2.
√20 = √(4 × 5) = 2√5
Nearby numbers
From 1 to 200
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How to read this
- The decimal is rounded; the surd form is the exact value.
- Pulling out a square factor simplifies the surd — √50 = 5√2.
- If the number is not a perfect square, the decimal never ends (irrational).
- Knowing which two integers it sits between is enough to estimate in your head.
Frequently asked questions
Q. What is the square root of 20?
About 4.472136, or exactly 2√5.
Q. Can the surd be simplified?
Yes: 20 = 4 × 5, so 2 comes out and it becomes 2√5.
Q. Between which integers does it fall?
Between 4 and 5.
Q. What is the cube root of 20?
About 2.714418.