2005 only July

[davidlucas580]

It seems my students are really interested in understanding how the calendar works over the years! Here we go:

The question highlights that while the date (July 1st) remains the same in the Gregorian calendar, the day of the week changes due to the 7-day week cycle and leap years.
For example, July 1st, 2005 was a Friday, while July 1st, 2025 will be a Tuesday. This is because 2025 is 20 years ahead of 2005, and 20 years includes 5 leap years, which results in a 5-day shift in the week (20 + 5 = 25, and 25 mod 7 = 4, so Friday + 4 days = Tuesday).
So the exact date (July 1st) remains the same in the Gregorian calendar, but the day of the week changes as the years go by. Also, time zones can influence the exact time at which the date is observed in different parts of the world, but the date (day and month) remains constant.
TRYING TO CLARIFY:
The expression "mod 7" refers to the modulo operation, which is used to find the remainder of dividing one number by another. In the case of "25 mod 7", we are dividing 25 by 7 and finding the remainder of that division.
Step by step:
1. Divide 25 by 7: 25 ÷ 7 = 3 (the quotient is 3). 2. Multiply the quotient by the divisor: 3 × 7 = 21. 3. Subtract the result from step 2 from the original number: 25 - 21 = 4. Therefore, 25 mod 7 = 4, which means that the remainder from dividing 25 by 7 is 4. Applying this to the context of days of the week, we have: - If April 1, 2005 was a Friday, adding 25 years (taking leap years into account) results in a shift of 25 days. - Since there are 7 days in a week, we use "mod 7" to find the corresponding day of the week after 25 days. - 25 mod 7 = 4, so 25 days after a Friday is a Tuesday (Friday + 4 days = Tuesday). NOTE:
The expression "mod 7" refers to the modulus operation, which is used to find the remainder of dividing one number by another. In the case of "25 mod 7", we are dividing 25 by 7 and finding the remainder of that division.
Here is the step-by-step process:
Divide 25 by 7: 25 ÷ 7 = 3 (the quotient is 3).
Multiply the quotient by the divisor: 3 × 7 = 21.
Subtract the result from step 2 from the original number: 25 - 21 = 4.
Therefore, 25 mod 7 = 4, which means that the remainder of dividing 25 by 7 is 4.