You know that that there are 24 hours in a day, 60 minutes in an hour, and 60 seconds in minute. But in 1973, France tried to make their own rule, they smashed the old clock in favor of French Revolutionary that divides the day into 10 decimal hours, each decimal hour into 100 decimal minutes and each decimal minute into 100 decimal seconds. France wanted to make the day have just 10 hours instead of 24.
So if a day is 70% complete, decimal time simply says "at the end of the seventh hour," whereas standard time requires us to say "at 16 hours, 48 minutes. French Revolutionary Time officially began on November 24, 1793. They might have changed this system but there is an advantage of it too. The time representation is simpler than the standard 24 hours's. Just 10 hours a day, if 2 hours are gone then it means 20% of a day is complete, it lets you remember important things.
So when it's 5, consider it as Noon.