Units of time
1 min (minute) = 60 s (seconds)
1 h (hour) = 60 min
1.5 h = $1{1/2}$h = 1 h 30 min
1 h = 60 × 60 s= 3600 s
day = 24 h
week = 7 days (Sunday, Monday, Tuesday, Wednesday, Thursday, Friday, Saturday)
month = from 28 to 31 days
| Month | Number of days |
| January | 31 |
| February | 28 or 29 |
| March | 31 |
| April | 30 |
| May | 31 |
| June | 30 |
| July | 31 |
| August | 31 |
| September | 30 |
| October | 31 |
| November | 30 |
| December | 31 |
year = 12 months = 365 days = 52 weeks 1 day
leap year = 12 months = 366 days = 52 weeks 2 days
A leap year is a year in which an extra day is added to the calendar in order to synchronize it with the seasons. In leap years, February 29th is added as leap day, which doesn't exist in a normal year (February has normally 28 days). A leap year occurs every 4 years - the year has to be evenly divided by 4 (
