# Is 1644 a Leap Year or a Common One? Does It Have 365 or 366 Days? The Algorithm and Steps To Calculate. The Last Leap Year Before 1644. The Next Leap Year After 1644. Leap Year Calculator

## Is 1644 a leap year or a common one? The last leap year before 1644 and the next leap year after 1644

### The leap year algorithm, three steps: [1] A year that is divisible by 4 (no remainder when divided by 4) is a leap year... [2] But if the year is also divisible by 100 (no remainder when divided by 100), it's not a leap year, unless... [3] ... Unless it's divisible by 400 (no remainder when divided by 400). A maximum of three steps to check, in this order

## The leap year algorithm. The three conditions to check in order to know whether a year is a leap or a common one

### 1) A year that is divisible by 4 (no remainder when divided by 4) is a leap year:

#### 1644 is divisible by 4 (no remainder when divided by 4).

### 2) In addition to step 1 above: If the year is divisible by 100 (no remainder when divided by 100) then it isn't a leap year:

#### 1644 is not divisible by 100 (there is a remainder when divided by 100).

#### We could have stopped at this step.

#### The year 1644 is a leap year and not a common one.

#### It does not meet this condition.

### 3) In addition to step 2 above: If the year is also divisible by 400 (no remainder when divided by 400) then it's a leap year:

#### 1644 is not divisible by 400 (there is a remainder when divided by 400).

## 1644 is a leap year.

The last leap year before 1644: 1640.

The next leap year after 1644: 1648.

### What is a leap year?

#### 1644, being a leap year has 366 days. A common year has 365.

#### In a leap year the month of February has 29 days. February 29th, 1644 is a valid date.

#### In a common year the month of February has 28 days. February 29th does not exist.

### Gregorian calendar (modern, civil)

#### The first year in the actual calendar (also called Gregorian, modern, civil) was 1582. Before this year another calendar (Julian) was in use, with different rules.

#### Not all the countries adopted the Gregorian calendar at the same time, in 1582. The adoption process took hundreds of years and is not even now complete.

#### The actual Gregorian calendar will get out of sync by 1 day with the astronomical calendar around the year of 4818 (after ≈ 3236 of years from its creation in 1582).

### How often do the leap years occur?

#### Nearly once every four years is a leap year. More exactly, leap years occur 97 times in every cycle of 400 years.

### Why do we need leap years in our calendar?

#### Leap years keep the calendar year in sync with the astronomical year, preventing us, for example, from celebrating Christmas in the month of November.

### More operations with Leap Years:

#### The last leap year before 1644: 1640.

#### The next leap year after 1644: 1648.

## Is it a leap year? The last and the next leap year, before and after the year

### The leap year algorithm. The three conditions to check in order to know whether a year is a leap or a common one:

#### 1) A year that is divisible by 4 (no remainder when divided by 4) is a leap year.

#### 2) But if the year is also divisible by 100 (no remainder when divided by 100), it's not a leap year, unless....

#### 3) ... Unless it's divisible by 400 (no remainder when divided by 400).