October 4, 2021 (Monday) to October 10, 2021 (Sunday)
Week 40 of 2021 runs from October 4, 2021 (Monday) to October 10, 2021 (Sunday). This is the 40th week of the year according to the ISO 8601 standard, in which weeks start on Monday.
Oct 4 is a Monday. It is the first day of Week 40 of 2021.
Oct 10 is a Sunday. It is the last day of Week 40 of 2021.
Oct 4 is in Week 40 of 2021 according to ISO 8601.
Oct 10 is in Week 40 of 2021 according to ISO 8601.
Week 40 of 2021 runs from October 4, 2021 to October 10, 2021.
Week 40 of 2021 starts on October 4, 2021, the 277th day of 2021.
Yes, all 7 days of Week 40 of 2021 fall within 2021.
2021 has 52 weeks according to ISO 8601.