Calendar Century Year Position Tool

Description

Return a positive Gregorian year coordinate's century and one-based position.

Civil calendar arithmetic needs explicit year numbering, leap rules and index origins. A weekday mask or Gregorian component operation does not identify a timezone, working calendar or historical calendar reform.

Return a positive Gregorian year coordinate's century and one-based position.

When to use this tool

Use Calendar Century Year Position when checking the stated weekday or Gregorian calendar convention.

How to use the tool and how it works

Enter year. Use the units and conventions below.
Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
Read century, position. Use the output convention below.

Return a positive Gregorian year coordinate's century and one-based position. Require year 1-9999; century = floor((year-1)/100)+1 and position = (year-1) modulo 100+1.^[1]

Input field	Meaning and units	Accepted input
year	Year	Required. Safe integer; minimum 1; maximum 9999.

Output field	Interpretation	Returned shape
century	Century	Required. Safe integer.
position	Position	Required. Safe integer.

json

{
  "input": {
    "year": 2000
  },
  "output": {
    "century": 20,
    "position": 100
  }
}

Limitations and assumptions

Century numbering has no year zero; this is not historical era or calendar conversion.
Inputs must satisfy both the field types and the cross-field conditions above. Invalid input causes an error; a successful false flag or documented placeholder is a different result.
Numeric calculations use binary floating point unless exact decimal-integer arithmetic is explicitly stated. No hidden measurement tolerance or decimal rounding is added; nonfinite or out-of-contract results are rejected. Numeric signed-zero results are exported as zero.

Alternative or Complementary methods

Use an appropriate full calendar library and authoritative local rules when business days, historical dates or real scheduling matter.

References

Calculation and input contract: date/calendar-century-year-position — tool.io

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