Friday, April 07, 2006

All numbers in a Row

There are 9 numbers between the number 1 and 9. Together, they make 9 digits.

There are 90 numbers between 10 and 99. They make 180 digits.

There are 900 between 100 and 999, and make 2700 digits.

9000 between 1000 and 9999 – 36000 digits.

90000 between 10000 and 99999 – 450000 digits.

Add up all the digits together. 9 + 180 + 2700 + 36000 + 450000 = 488,889. This is how many digits I will have written when I reach the number 99,999. This is the last 5 digit number. Since I am trying to reach 2,000,000 numbers, and have already written 488,889, then 2,000,000-488,889=1,511,111 is how many digits I have yet to write. Since 99,999 was the last 5 digit number, I will be writing 6-digit numbers to make 1,511,111 digits. This means that I will be writing 1,511,111/6=251,851R5 6-digit numbers. The first 6-digit number is 100,000. That means I will be writing 251,851R5 numbers after 100,000, so the last 6-digit number will be 251,851R5+100,000=351,851R5.

351,851 351,852. 5 will be the 2 millionth digit in the long string of numbers, and this 5 is part of the 6-digit number 351,852.

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