April 10th is the 100th day of this year (2009). During leap years, however, the 100th day of those years will occur on April 9th. This type of information is obtained by consulting a Julian calendar - a calendar that shows, besides normal information, the number of days which have elapsed (and usually also how many are remaining) in the current year.
The one hundredth day of the year is typically April 10th in a common year and April 9th in a leap year. This is based on the calendar, where January has 31 days, February has 28 days (or 29 in a leap year), March has 31 days, and April has 30 days. Thus, counting the days leads to April 10th as the 100th day of the year in most years.
One hundredth of a century is a year.
If you want that sort of precision then you need to specify whether you want the number of days in a solar year, a siderial year, a synodic year, a tropical year.
century centenary centennial
The answer depends on when school started, how many holidays, how many teacher training (INSET in UK) days.
The one hundredth day of a non-leap year is April 10.
The two hundredth day of a leap year is July 18.
The 10th of April in an ordinary year and the 9th of April in a leap year.
The one hundredth day of the year is typically April 10th in a common year and April 9th in a leap year. This is based on the calendar, where January has 31 days, February has 28 days (or 29 in a leap year), March has 31 days, and April has 30 days. Thus, counting the days leads to April 10th as the 100th day of the year in most years.
One hundredth of a century is a year.
homework for day 101
If you want that sort of precision then you need to specify whether you want the number of days in a solar year, a siderial year, a synodic year, a tropical year.
April 20th
The 10th of April in a normal year and the 9th of April in a leap year.
a century
1900 is the last year (the hundredth year) of the 19th century.
one hundredth 1/100