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Calculate Square Root Without a Calculator

Newton's Method Approximation:

\[ x_{n+1} = \frac{1}{2}\left(x_n + \frac{S}{x_n}\right) \]

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1. What is Newton's Method?

Newton's method (also called the Newton-Raphson method) is an iterative algorithm for finding successively better approximations to the roots (or zeroes) of a real-valued function. For square roots, it provides a fast-converging sequence of approximations.

2. How Does the Calculator Work?

The calculator uses Newton's method equation:

\[ x_{n+1} = \frac{1}{2}\left(x_n + \frac{S}{x_n}\right) \]

Where:

Explanation: The method starts with an initial guess (typically S/2) and iteratively improves the estimate by averaging the guess with S divided by the guess.

3. Importance of Square Root Calculation

Details: Square roots are fundamental in mathematics, physics, engineering, and computer science. Understanding manual calculation methods helps build intuition about numerical algorithms and approximation techniques.

4. Using the Calculator

Tips: Enter a non-negative number and the number of iterations (typically 5-10 gives good results for most numbers). More iterations provide more precise results but have diminishing returns.

5. Frequently Asked Questions (FAQ)

Q1: Why use Newton's method instead of other approaches?
A: Newton's method converges quadratically (number of correct digits roughly doubles with each iteration), making it very efficient.

Q2: What's a good initial guess?
A: For positive numbers, S/2 is a simple and effective initial guess. Other methods might use the number itself or 1 as starting points.

Q3: How many iterations are needed?
A: Typically 5-10 iterations provide excellent precision for most practical purposes. The calculator shows each step so you can see convergence.

Q4: Does this work for negative numbers?
A: No, the square root of a negative number is complex. This calculator only handles non-negative real numbers.

Q5: How accurate is this compared to calculator sqrt() functions?
A: With enough iterations, it can be just as accurate. Most calculators use similar approximation methods internally.

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