1 first of all, the content of the interesting mathematics handwritten newspaper is written as -h, and the hour is an auxiliary time unit coordinated with the basic unit of the international system of units. Except in leap second, one hour is equal to 3600 seconds, or 60 minutes, or 1/24 days, which is often represented by "h" in English or mathematics.

2, the second minute-min, the English word is minute, which originally means "tiny" and also means min.

3, the last second -s, the second is the basic unit of time in the international system of units, the symbol is S, and sometimes it is marked as sec with English abbreviations.