√ Square Root of 84 = 9.165
The square root of 84 is a value that when multiplied by itself gives 84. Learn 5 different methods to calculate √84 with step-by-step explanations.
What Is √84 and Why It Matters
The square root of 84 is 9.165 because 9.165 × 9.165 ≈ 84. 84 is not a perfect square, so its square root is an irrational number that continues forever without repeating. The simplified radical form is 2√21.
Understanding √84 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 √84
Choose the method that works best for you, from simple mental math to advanced approximation techniques.
Mental Math (Multiplication)
Find the closest perfect squares: 9² = 81 and 10² = 100. Since 84 is between these, estimate around 9.165.
Prime Factorization
Prime factors: 84 = 2 × 2 × 3 × 7. Simplify: √84 = 2√21.
Long Division
Pair digits from right: 84 → 84. Continue with decimal pairs. Answer: 9.165151
Newton-Raphson (Iterative)
Formula: x₁ = (x₀ + n/x₀)/2. Starting with 9: iterations converge to 9.165.
Scientific Calculator
Press √, then 84, then = or Enter. Result: 9.165151.
Method Comparison
| Method | Best For | Result | Difficulty |
|---|---|---|---|
| Mental Math | Quick estimates | 9.165 | Easy |
| Prime Factorization | Simplifying radicals | 2√21 | Medium |
| Long Division | Exact decimals | 9.165151 | Hard |
| Newton-Raphson | Programming | 9.165 | Hard |
| Calculator | Everyday use | 9.165151 | Easy |
Real-World Uses of √84
Geometry & Area
A square with area 84 cm² has side length 9.165 cm. This is a classic example used in math classes worldwide.
Construction & Architecture
Builders and architects use √84 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 84 is 9.165. Since 9.165 × 9.165 ≈ 84, this is an irrational number with infinite decimal places.
We've explored 5 different methods to calculate √84, 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."