A month with 3 1 day is a big month, and there are seven big months every year, namely 1, March, May, July, August, 10, 12.

There are 30 days of abortion in a month, and there are four abortions every year, which are April, June, September, 165438+ 10.

(2) February is neither a big moon nor a small moon.

(3) We can record the month in two ways:

The first is the fist memory method. (Use the bulges of fist joints to practice finger boxing, as shown in P 18: January and February are not too big, March is big, April is small, May is big, June is small, July is big, August is big, September is small, October is big, November is small, and December is big. )

The second is the formula: the first seven months, the last eight months.

(4) July and August, 65438+February and 65438+1October are consecutive big months.

If the same year is emphasized, then only July and August are consecutive big months.

Continuous months add up to 62 days.

A big moon and a small moon add up to 6 1 day.

(5) 7 days a week, with at least 4 Sundays and at most 5 Sundays a month.

(6) Add the date every seven days, and the day of the week is the same.

For example, June 1 is Wednesday, so June 8 is Wednesday, and June 15 is also Wednesday.

(7) A year with only 28 days in February is a normal year, and a normal year has 365 days.

A year with 29 days in February is a leap year and a leap year has 366 days.

There are three normal years and 1 leap years every four years.

(8) Usually the Gregorian calendar year is a multiple of 4 (there is no remainder when divided by 4), which is a leap year.

But the Gregorian calendar year is an integer (with two zeros at the end), and it must be a multiple of 400 (divided by 400 without remainder) to be a leap year.

Exercise: 1996, 2 100, 1960, 20 10, 2009, 1978, which years are normal years and which years are leap years.

There are four quarters in a year.

The first quarter is 65438+ 10, February and March, and the first quarter of a normal year has 90 days.

The first quarter of leap year has 9 1 day.

The second quarter is April, May and June, and it is fixed in days and columns every year.

The third quarter is month, month and month, and every year is a fixed day and column.

The fourth quarter is month, month and month, and every year is a fixed day and column.

(10) There are 7 days in a week, and 365 days in a normal year have 0 days in a week.

In the 366 days of leap year, there are consecutive 10 weeks and 0 days.