If I took all the numbers from one to one billion:
 How many of them contain at least one '1'?
 If I wrote them out in one long line, how many 1 digits would there be?
(In reply to
Solutions by Federico Kereki)
The fraction of numbers in the range 000,000,000 to 999,999,999 that do not have a 1 in any position can be calculated as .9^9. So the number that do have at least one 1 number 1,000,000,000*(1.9^9), and then add 1 for 1,000,000,000. This agrees with Federico's summation and with Penny's result: 612,579,512.

Posted by Charlie
on 20040726 10:50:27 