To find a relative date, 3 weeks in the future from 13th November, you can manually calculate it by adding 21 days to the given date. Begin by determining the total number of days in November, which is 30 days. Then, subtract 13 days from the total to get the remaining days in November (30 – 13 = 17 days). Since 17 days are left in November, you need to add 4 more days to reach the end of November and proceed to December.

Continue the calculation by adding the remaining 17 days in November to the additional 4 days needed to complete November, which gives you a total of 21 days. Therefore, starting from 13th November, moving ahead 21 days brings you to 4th December, marking the relative date 3 weeks in the future. This manual calculation ensures precision when determining future dates based on a given starting point.