The number of 90-degree angles is twice per hour, and * * * counts as 48 times.
(2) The minute hand goes once, and the hour hand goes112 times.
Starting from 1, the minute hand coincides with the hour hand when it takes x laps.
X =112+x/12 (moving distance of minute hand = position of hour hand at 65438+moving distance)
1 1/ 12 x = 1/ 12
x = 1/ 1 1
The minute hand went111turn, which is 60/1/minute.
The first coincidence is at 1: 60/ 1 1 min.
Year-Month-Day Mathematical Story Knowledge "Year-Month-Day" and "Year" related knowledge points: 1, year = 12 months and a half =6 months, average year =365 days, leap year =366 days. 2. Judge the normal year and leap year: Method: leap four years, not leap one hundred years, leap four hundred years.
For example: 1968- leap year, 1954- flat year, 1900- flat year, 2000- leap year. Judgment method: If the last digit of the year is odd 1, 3, 5, 7, 9, it must be a normal year, such as: 201,1985 ... If the last digit of the year is even, further judgment is needed. There are two simple ways: (1) to see if the last two digits can be judged. Another example is: 19 18, and the last two digits are 18 ÷ 4 = 4...2, so it is a normal year.
(2) Remember that the special year 2000 is a leap year. Difference it with the year to be judged, such as: 1996,2000-1996 = 4, 4 can be evenly divided by 4 (multiple of 4), so it is a leap year; Another example: 20 16, 20 16-2000 = 16, 16 can be divisible by 4 (multiple of 4), so it is a leap year.
3. Calculate anniversary: Method: Last year-initial year = anniversary. For example, 20111kloc-0/is the 62nd anniversary of the founding of People's Republic of China (PRC). 2011-1949 = 62 (anniversary), for example, June 8, 20 12 is Xiaoming's ninth birthday. What year was he born? 20 1 2-9 = "month" in 2004 (year):1,big month =365438+ 0 days in the whole year * * There are 7 big months and small months = 30 days in the whole year * * There are 4 small months and a half months = 15 balanced year.