Draft:Leibniz Series enhancement for first graders.

• Comment: Fails WP:GNG, lacks any sources or references. Dan arndt (talk) 03:29, 14 August 2024 (UTC)

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It is common knowledge (no reference needed) that Gottfried Leibniz used the expression for (arc tangent = 1) to show that 1 - 1/3 + 1/5 - 1/7 ... if carried to infinity will converge on the value of Pi/4. But to use it to calculate the value of Pi you first convert the equation to Pi = 4 - 4/3 + 4/5 - 4/7 ... then you must calculate the decimal value of the first 5 fractions and create a cumulative sum as shown below. Then you must find the average of each pair of consecutive sums and (which will give you one less average than the number of cumulative sums you choose). Obviously,the average between two consecutive sums will be closer to the value of Pi than either of the cumulative sums from which you find the average. You continue in this manner finding averages and averages of averages until you finally have only one average and that will be closer to Pi than any of the previously calculated averages. Below I have demonstrated this with a limited number of pairs of consecutive sums, using only the four pairs of cumulative sums. This can all be done by a class of first graders who know how to divide by a single digit divisor, and divide by 2, to give and approximation of Pi that rounds to 3.14 (as is demonstrated int the table below)

1.+4/1 +4.0000

2 -4/3 -1.3333 2.6667

3 +4/5 +0.8000 3.4667 3.0669

4 -4/7 -0.5714 2.8953 3.1810 3.1240

5 +4/9 +0.4444 3.3397 3.1175 3.1493 3.1366

Notice that 3.1366 rounds to 3.14

At least one teacher I am aware of has used this to introduce Pi to a second grade class but it could be done with a first grade class where some children calculate 4/3, some calculate some 4/5 and the they cooperate to do the calculations of cumulative sums and the averages. In conjunction with this a wooden circle was rolled on the floor to show that the fractional part is close to 1/7 of the diameter of the circle to verify that the calculations agree with actual measurement of Pi.

This method of approximating Pi is not nearly as efficient as other more complex methods but it arrives at a good approximation of Pi faster and with less complexity than using the polygon method that requires taking square root and does not lend itself to "distributing processing".

(The numbers speak for themselves but if it is felt that references are needed to show that Leibniz actually found this to converge to Pi, I can furnish many references right here on Wikipedia that states this to be true. Let me know and I will furnish them. Most people who are at all familiar with the history of Pi will be familiar with this series.)