This is today's date on the regular (Gregorian) calendar:

…and this is the same date on the World calendar:

…and on the International fixed calendar:

What about a decimal calendar?

Decimal calendars have been attempted, but none have gathered much interest. Some had 10 months of ~36 days, some kept the 12 months, but divided them into 3 weeks of 10 days where the 5 or 6 extra days (to match a solar year) happen after the last month.