A Homogeneous Date

May 5 of 1955 can be written as 5/5/55. How many times during the 20th century the date in the format month day and the last two digits of the year can be written with the same digit?



  1. Kk:

    N.n.nn -9 dates, 11.1.11, 1.11.11, 11.11.11, 2.22.22.

  2. Andrew:

    Thirteen times. Four with only the digit 1, two with only the digit 2, and one each for the digits 3 through 9.

  3. Leif:

    I think there’s more – something like 6/9/96 is all written with the same digit (although I’ve had to turn the paper upside down occasionally).

  4. Ted Ridgway:

    I can do 90.

    Using base 2.

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