√ Square Root of 402 = 20.05
The square root of 402 is a value that when multiplied by itself gives 402. Learn 5 different methods to calculate √402 with step-by-step explanations.
What Is √402 and Why It Matters
The square root of 402 is 20.05 because 20.05 × 20.05 ≈ 402. 402 is not a perfect square, so its square root is an irrational number that continues forever without repeating. The simplified radical form is √402.
Understanding √402 helps build a strong foundation in algebra, geometry, and advanced mathematics. Whether you're a student learning square roots, a teacher preparing lessons, or a professional needing quick math references, this guide covers everything you need to know.
5 Ways to Calculate √402
Choose the method that works best for you, from simple mental math to advanced approximation techniques.
Mental Math (Multiplication)
Find the closest perfect squares: 20² = 400 and 21² = 441. Since 402 is between these, estimate around 20.05.
Prime Factorization
Prime factors: 402 = 2 × 3 × 67. Simplify: √402 = √402.
Long Division
Pair digits from right: 402 → 402. Continue with decimal pairs. Answer: 20.049938
Newton-Raphson (Iterative)
Formula: x₁ = (x₀ + n/x₀)/2. Starting with 20: iterations converge to 20.05.
Scientific Calculator
Press √, then 402, then = or Enter. Result: 20.049938.
Method Comparison
| Method | Best For | Result | Difficulty |
|---|---|---|---|
| Mental Math | Quick estimates | 20.05 | Easy |
| Prime Factorization | Simplifying radicals | √402 | Medium |
| Long Division | Exact decimals | 20.049938 | Hard |
| Newton-Raphson | Programming | 20.05 | Hard |
| Calculator | Everyday use | 20.049938 | Easy |
Real-World Uses of √402
Geometry & Area
A square with area 402 cm² has side length 20.05 cm. This is a classic example used in math classes worldwide.
Construction & Architecture
Builders and architects use √402 to calculate diagonal measurements, ensure right angles, and determine material quantities.
Statistics & Data Science
Standard deviation, variance, and other statistical measures frequently use square root calculations for data analysis.
Physics & Engineering
Square roots are essential in calculating velocity, acceleration, electrical resistance, and many scientific formulas.
Continue Your Learning Journey
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Frequently Asked Questions
Practice Problems
Final Thoughts
The square root of 402 is 20.05. Since 20.05 × 20.05 ≈ 402, this is an irrational number with infinite decimal places.
We've explored 5 different methods to calculate √402, from simple mental math to advanced iterative techniques. Each method offers a unique approach to understanding this fundamental mathematical concept.
"Mastering square roots opens the door to advanced mathematics and real-world problem solving."