Sorry, but i think all above are wrong!! since they calculate some numbers twice!!
between 1 and 100 we have 3,13,23,43,53,63,73,83,93 = 9 times
and we have the numbers 30-39 = 10 times which gives us total of 19 nunbers!! (not 20)
So between 0 and 1000 this metod will repeat itself 9 times for, 0-99, 100-199, 200-299, 400...
and that will five us 9*19=171 and we have 100 nunbers 300-399
so the correct answer is 271!! not 300
the mistake of "veekay" was that we only have 27 combinations in which 3 appears twice in the number and not 54
so the calculation is 243 (for 1 digit only) + 27 (for 2 digits only) + 1 (for 333)=271!!
Sorry guys, i was wrong since i forgot that between 30-39 we have 11 times the digit 3, and between 300-399 we have 120 times the digit 3 so it comes up to 300 times in total.
Last edited by
moshe.k on Sun Jun 25, 2017 2:48 am, edited 1 time in total.