The Babylonian method of finding square roots

G'day G'day Folks,

The Babylonians had a method of calculating square roots which is now often known as Heron's method after Heron of Alexandria. I like it because it is fun to implement on a Casio 82TL calculator. These are one of the least expensive calculators on the market yet do most algebraic calculations.

Let us find the square root of a real integer, R.

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For example let’s find  

Step 1. Find the largest integer  such that,  

 

On the Casio 82TL simply enter, 3 =

The importance of this step is that 3 is stored as the first answer.

Step 2. Improve the estimate.

  

 ANS = the previous answer, which in the first instance is 3.

On the Casio 82 TL the previous answer is given automatically by the ANS key .

What makes the process fun to do is that the Casio 82TL has a fraction key.  

This allows fractions to be entered as written.

 

 

 

 

Amazing as it may seem to get the next approximation simply press the = key. 

The Casio 82 TL substitutes in the previous approximation into the same expression.

 

The magic continues as the = key is pressed again.

 

The answer is displayed as a decimal when fractions exceed three digits.

The fourth approximation,  agrees with the Casio 82TL calculator’s evaluation of  to 8 decimal places.

Have fun and let me know how easy this is to read.  

 

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