Define a period

...

How many working days in year 1998?

Here is the detail of the calculation:

Because 1998 is not a leap year, it has 365 days.

Let's remove 52 saturdays and 52 sundays. It remains 261 days.

Now, let's remove 14 public holidays that do not fall during a weekend and we obtain 247 working days in 1998.

Here is the list of these 14 public holidays:

1. New Year's Day : Thursday, 1 January, 1998
2. Coming of Age Day : Monday, 12 January, 1998
3. Foundation Day : Wednesday, 11 February, 1998
4. Vernal Equinox Day : Friday, 20 March, 1998
5. Shōwa Day : Wednesday, 29 April, 1998
6. Greenery Day : Monday, 4 May, 1998
7. Children's Day : Tuesday, 5 May, 1998
8. Marine Day : Monday, 20 July, 1998
9. Respect-for-Aged Day : Monday, 21 September, 1998
10. Autumnal Equinox Day : Wednesday, 23 September, 1998
11. Health and Sports Day : Monday, 12 October, 1998
12. Culture Day : Tuesday, 3 November, 1998
13. Labor Thanksgiving Day : Monday, 23 November, 1998
14. Emperor's Birthday : Wednesday, 23 December, 1998

And here is the public holiday falling on a weekend:

1. Constitution Memorial Day : Sunday, 3 May, 1998