√24 at a glance
- Exact value
- 2√6
- Decimal (10 places)
- 4.8989794856
- Rounded
- 4.9 · 4.90 · 4.899
- Perfect square?
- No — between 4² and 5²
- Rational?
- Irrational
- Both square roots
- ±4.898979
- Prime factorization
- 2³ × 3
- Cube root
- 2.884499
How to simplify √24
Look for the largest perfect square that divides 24. Here it is 4 (2²), because 24 = 4 × 6 and 6 has no square factor left:
The prime factorization tells the same story: 24 = 2³ × 3. Each pair of equal primes leaves the radical as one factor, so 2 comes out and 2 × 3 stays inside.
Check: (2√6)² = 2² × 6 = 4 × 6 = 24. As a decimal, 2√6 = 2 × 2.4494897428 ≈ 4.8989794856.
Where √24 sits between perfect squares
16 = 4² and 25 = 5² are the nearest perfect squares, so √24 lies between 4 and 5. 24 is 8 above 16 and 1 below 25, so the root is closer to 5.
- Straight line between 16 and 25: 4.8889 (0.21% low)
- Tangent from 4, i.e. 4 + 8 ÷ 8: 5.0000 (2.06% high)
- Tangent from 5, i.e. 5 − 1 ÷ 10: 4.9000 (0.02% high)
For √24 the tangent at 5 wins, missing by only 0.001. Tangent estimates shine when the number sits close to a perfect square — here 24 is just 1 below 25.
Finding √24 with the Babylonian method
Picture a rectangle with an area of 24 and one side x; the other side must be 24 ÷ x. Averaging the two sides gives a rectangle that is closer to a square, and the side of that square is exactly √24.
Start from the nearest whole number, 5 (5² = 25):
| Step | Guess x | 24 ÷ x | Average | Correct decimals |
|---|---|---|---|---|
| 1 | 5.0000000000 | 4.8000000000 | 4.9000000000 | 2 |
| 2 | 4.9000000000 | 4.8979591837 | 4.8989795918 | 6 |
| 3 | 4.8989795918 | 4.8989793793 | 4.8989794856 | all 10 shown |
The count of correct decimals went 2, 6 and all 10 over 3 steps — roughly doubling each time — until the guess matched √24 = 4.8989794856 to every decimal shown.
√24 as a continued fraction
Every irrational square root has a continued fraction that repeats. For √24 the pattern is [4; 1, 8] with the block of 2 terms after the semicolon repeating forever. A pattern that never ends is one more proof that √24 is irrational.
Cutting the continued fraction off early gives the best fractions for approximating the root — no fraction with a smaller denominator comes closer:
| Fraction | Decimal | Error |
|---|---|---|
| 4/1 | 4.0000000000 | 9.0 × 10⁻¹ |
| 5/1 | 5.0000000000 | 1.0 × 10⁻¹ |
| 44/9 | 4.8888888889 | 1.0 × 10⁻² |
| 49/10 | 4.9000000000 | 1.0 × 10⁻³ |
| 436/89 | 4.8988764045 | 1.0 × 10⁻⁴ |
| 485/99 | 4.8989898990 | 1.0 × 10⁻⁵ |
The same fractions solve Pell’s equation, x² − 24y² = 1. Its smallest solution in positive whole numbers is x = 5, y = 1.
√24 in geometry and everyday measurements
- A square tile with an area of 24 square inches has sides about 4.899 in long.
- 24 is not a sum of two whole-number squares — the prime factor 3 (one less than a multiple of 4) appears an odd number of times, which rules that out — so √24 is never the diagonal of a rectangle with whole-number sides. It is, however, the space diagonal of a 2 × 2 × 4 box, because 2² + 2² + 4² = 24.
- Since √24 = 2√6, a length of √24 is exactly 2 copies of the length √6 laid end to end.
Square roots near √24 and related roots
| Root | Simplest form | Decimal | Perfect square? |
|---|---|---|---|
| √21 | √21 | 4.5826 | No |
| √22 | √22 | 4.6904 | No |
| √23 | √23 | 4.7958 | No |
| √24 | 2√6 | 4.8990 | No |
| √25 | 5 | 5.0000 | Yes |
| √26 | √26 | 5.0990 | No |
| √27 | 3√3 | 5.1962 | No |
- The cube root of 24 is about 2.884499.
- Four times the radicand doubles the root: √96 = 2 × √24 ≈ 9.797959.
Frequently asked questions
What is the square root of 24?
The square root of 24 is 2√6 in simplest radical form, which is about 4.8989794856. The negative root, −4.898979, also squares to 24.
Is the square root of 24 rational or irrational?
Irrational. 24 is not a perfect square — it falls between 16 and 25 — and the square root of any whole number that is not a perfect square cannot be written as a fraction.
Can √24 be simplified?
Yes. The largest perfect square dividing 24 is 4, so √24 = √4 × √6 = 2√6.
What is √24 rounded to two decimal places?
√24 ≈ 4.90 to two decimal places (4.9 to one, 4.899 to three). Check: 4.90² = 24.01, close to 24.