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A brief overview of the first 10 million characters of Pi

Introduction



Recently I came across this video:







In it, the British guys talk about how they printed the Pi number up to a million mark on a paper tape, and then rolled it out on the runway. It turned out the tape length of 1.69 km. For orientation in this set of digits every 10 characters is the corresponding label.



During their event, the authors tell about interesting places of Pi. So, on the 762nd symbol begins the so-called. Feynman point . The nearest sequence consisting of the same numbers, longer than this will be only 710000 digits.

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One of the commentators shared a link and added "Learn." This story is devoted to such a superficial study of the first 10 million characters of Pi.



Overview



The first thought is, of course, to count how many times units, twos, etc. meet here. Intuition suggests that the number of meetings with each digit should be about a million. Slightly less lazy readers can apply mathematical statistics techniques when processing results, but I will confine myself to the following table.



NumeralNumber of meetings
0999440
one999333
21000306
3999965
four1001093
five1000466
6999337
71000207
eight999814
910,00040


Here, exactly in half of the cases, the number of meetings is greater than expected. Expected.



Next, let's see how often in our number there are pairs, twos, triples, etc. same numbers. The results are shown in a similar table. Eight in a row any identical numbers are not found in the considered number of characters Pi.



NumeralTwo in a rowThree in a rowFour in a rowFive in a rowSix in a rowSeven in a row
0986389669872876one
one986899629976101tenone
29896997759488490
3995529831934877one
four98934958389187eight0
five994839953100697eleven2
6988679599940969one
79919497801004112142
eight98761964191192sixteen2
9991129977100510317four


From the interesting here: continuous sequences of nines are more common. And 999999 appears more often 000000 almost three times.



And finally, a brief look at what other sequences are found in Pi. So, once there is a series of 1234567 , which is the longest sequence in a row arranged in ascending order of numbers. If we look for rows of digits arranged in descending order, then the longest of them is 876543210 and it occurs once.



Instead of conclusion



Next, I decided to see how the number Pi intersects with other known constants. So, the first 6 digits of the number e (e = 2.71828) are found 7 times, like the first 6 digits of Pi himself. It would be interesting to look for intersections of known constants, but the research method applied here (Ctrl + F at pi.karmona.com ) is not suitable for this. One of the databases of known constants is oeis.org .



Thanks for attention.

Source: https://habr.com/ru/post/362573/



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