Printable worksheet

← Back to the Day of the Year Calculator

In the print window, choose “Save as PDF” as the printer (or print it on paper). Seed 1 rebuilds this exact sheet.

Day of the Year worksheet

Grades 3–4

Solve each problem and show your work. Round answers to 2 decimal places where needed.

1.
Problem 1.
- What do you want to find?: Date of a day number
- Year: 2,000
- Day number: 105
Find: Date
Answer
2.
Problem 2.
- What do you want to find?: Date of a day number
- Year: 1,700
- Day number: 80
Find: Date
Answer
3.
Problem 3.
- What do you want to find?: Day number of a date
- Date: Aug 17, 2026
Find: Day of the year
Answer
4.
Problem 4.
- What do you want to find?: Day number of a date
- Date: May 13, 2025
Find: Day of the year
Answer
5.
Problem 5.
- What do you want to find?: Day number of a date
- Date: Nov 18, 2025
Find: Day of the year
Answer
6.
Problem 6.
- What do you want to find?: Date of a day number
- Year: 1,800
- Day number: 100
Find: Date
Answer
7.
Problem 7.
- What do you want to find?: Day number of a date
- Date: Aug 19, 2026
Find: Day of the year
Answer
8.
Problem 8.
- What do you want to find?: Date of a day number
- Year: 1,800
- Day number: 75
Find: Date
Answer
9.
Problem 9.
- What do you want to find?: Date of a day number
- Year: 1,300
- Day number: 120
Find: Date
Answer
10.
Problem 10.
- What do you want to find?: Day number of a date
- Date: Aug 10, 2025
Find: Day of the year
Answer

Answer key: Day of the Year worksheet

1. Date: Apr 14, 2000
1. 2000 is a leap year with 366 days, so day 105 is within it
  $days in 2000$ $= 366$
2. Subtract the 91 days of the months before April
  $105 - 91$ $= 14 April$
3. Write out the date and its weekday
  $day 105$ $= Apr 14, 2000 (Friday)$
2. Date: Mar 21, 1700
1. 1700 is a common year with 365 days, so day 80 is within it
  $days in 1700$ $= 365$
2. Subtract the 59 days of the months before March
  $80 - 59$ $= 21 March$
3. Write out the date and its weekday
  $day 80$ $= Mar 21, 1700 (Sunday)$
3. Day of the year: 229
1. Add up the days in each full month before August (February has 28 days in 2026), then add the day of the month
  $31 + 28 + 31 + 30 + 31 + 30 + 31 + 17$ $= 229$
2. Take the day number away from the 365 days in 2026 to see how many days are still to come
  $365 - 229$ $= 136 days$
3. Divide by the days in the year to see how much of the year is done by the end of this day
  $\frac{229}{365} \times 100$ $= 62.74%$
4. For the ISO week number, find the Thursday of this Monday-to-Sunday week, then count weeks from the start of that Thursday's year
  $ISO week$ $= 34$
4. Day of the year: 133
1. Add up the days in each full month before May (February has 28 days in 2025), then add the day of the month
  $31 + 28 + 31 + 30 + 13$ $= 133$
2. Take the day number away from the 365 days in 2025 to see how many days are still to come
  $365 - 133$ $= 232 days$
3. Divide by the days in the year to see how much of the year is done by the end of this day
  $\frac{133}{365} \times 100$ $= 36.44%$
4. For the ISO week number, find the Thursday of this Monday-to-Sunday week, then count weeks from the start of that Thursday's year
  $ISO week$ $= 20$
5. Day of the year: 322
1. Add up the days in each full month before November (February has 28 days in 2025), then add the day of the month
  $31 + 28 + 31 + 30 + 31 + 30 + 31 + 31 + 30 + 31 + 18$ $= 322$
2. Take the day number away from the 365 days in 2025 to see how many days are still to come
  $365 - 322$ $= 43 days$
3. Divide by the days in the year to see how much of the year is done by the end of this day
  $\frac{322}{365} \times 100$ $= 88.22%$
4. For the ISO week number, find the Thursday of this Monday-to-Sunday week, then count weeks from the start of that Thursday's year
  $ISO week$ $= 47$
6. Date: Apr 10, 1800
1. 1800 is a common year with 365 days, so day 100 is within it
  $days in 1800$ $= 365$
2. Subtract the 90 days of the months before April
  $100 - 90$ $= 10 April$
3. Write out the date and its weekday
  $day 100$ $= Apr 10, 1800 (Thursday)$
7. Day of the year: 231
1. Add up the days in each full month before August (February has 28 days in 2026), then add the day of the month
  $31 + 28 + 31 + 30 + 31 + 30 + 31 + 19$ $= 231$
2. Take the day number away from the 365 days in 2026 to see how many days are still to come
  $365 - 231$ $= 134 days$
3. Divide by the days in the year to see how much of the year is done by the end of this day
  $\frac{231}{365} \times 100$ $= 63.29%$
4. For the ISO week number, find the Thursday of this Monday-to-Sunday week, then count weeks from the start of that Thursday's year
  $ISO week$ $= 34$
8. Date: Mar 16, 1800
1. 1800 is a common year with 365 days, so day 75 is within it
  $days in 1800$ $= 365$
2. Subtract the 59 days of the months before March
  $75 - 59$ $= 16 March$
3. Write out the date and its weekday
  $day 75$ $= Mar 16, 1800 (Sunday)$
9. Date: Apr 30, 1300
1. 1300 is a common year with 365 days, so day 120 is within it
  $days in 1300$ $= 365$
2. Subtract the 90 days of the months before April
  $120 - 90$ $= 30 April$
3. Write out the date and its weekday
  $day 120$ $= Apr 30, 1300 (Friday)$
10. Day of the year: 222
1. Add up the days in each full month before August (February has 28 days in 2025), then add the day of the month
  $31 + 28 + 31 + 30 + 31 + 30 + 31 + 10$ $= 222$
2. Take the day number away from the 365 days in 2025 to see how many days are still to come
  $365 - 222$ $= 143 days$
3. Divide by the days in the year to see how much of the year is done by the end of this day
  $\frac{222}{365} \times 100$ $= 60.82%$
4. For the ISO week number, find the Thursday of this Monday-to-Sunday week, then count weeks from the start of that Thursday's year
  $ISO week$ $= 32$