How many odd days are there from 2004 to 2008 year?

Odd days are the days left over once complete weeks are removed from a total day count. An ordinary year has 365 days, and 365 mod 7 = 1, so it contributes 1 odd day; a leap year has 366 days, and 366 mod 7 = 2, so it contributes 2 odd days. The number of odd days over a span of years is the sum of each individual year's contribution.

1. 2004 is a leap year (divisible by 4), so it contributes 2 odd days.

2. 2005 is an ordinary year, so it contributes 1 odd day.

3. 2006 is an ordinary year, so it contributes 1 odd day.

4. 2007 is an ordinary year, so it contributes 1 odd day.

5. 2008 is a leap year (divisible by 4), so it contributes 2 odd days.

6. Summing these contributions: 2 + 1 + 1 + 1 + 2 = 7.

Cross-check by grouping years instead of listing each one: from 2004 to 2008 there are exactly two leap years (2004 and 2008) and three ordinary years (2005, 2006, 2007). So total odd days = (2 leap years x 2) + (3 ordinary years x 1) = 4 + 3 = 7, which matches the year-by-year sum above.

Hence, the number of odd days from 2004 to 2008 is 7.