How many odd days are there in a leap year? (“Odd days” means total days modulo 7 in that period.)

Introduction / Context:
In calendar arithmetic, “odd days” are the count of days modulo 7. They determine the weekday shift between two dates. A year’s odd days equal year length mod 7.

Given Data / Assumptions:

• Leap year length = 366 days.
• Odd days = 366 mod 7.

Concept / Approach:
Compute the remainder when dividing 366 by 7 to find how many weekdays forward the calendar shifts from one year to the next (e.g., Jan 1 to Jan 1 next year).

Step-by-Step Solution:

Verification / Alternative check:
Common year (365 days) has 1 odd day since 365 = 52*7 + 1; leap year adds the extra day making 2 odd days.

Why Other Options Are Wrong:
1 is for common years; 3 or 4 would require longer cycles than a leap year provides.

Common Pitfalls:
Confusing “odd days” with weekend days; “odd” here strictly means remainder by 7, not parity.

Final Answer:
2.