Question

Find the cardinal number of the following set.

S = The set of all leap years between 1882 and 1906.

Answer 1

A year is a leap year if:

It is divisible by 4.

1884, 1888, 1892, 1896, 1900, 1904

The year 1900 is a century year. According to the Gregorian calendar rules, we divide it by 400:

`1900/400`

= 4.75

Since 1900 is not perfectly divisible by 400, 1900 was not a leap year.

S = {1884, 1888, 1892, 1896, 1904}

n(S) = 5