Dates can be written as month/day/year using integers 1 through 12 for the month, followed by the day of the month, followed by the last two digits of the year. The date 12/ 3/ 45 is an increasing sequence of consecutive digits, while 1/ 22/ 34, 1/ 2/ 35, 1/ 2/ 03 are not. For how many days where the year ends in 9 is the date an increasing sequence of consecutive digits?

Guest Oct 25, 2020