To manually calculate the number of minutes in 23 days, you can multiply the number of days by the number of hours in a day and then by the number of minutes in an hour. There are 60 minutes in an hour and 24 hours in a day. Therefore, the calculation would be: 23 days x 24 hours/day x 60 minutes/hour. This results in a total of 33,120 minutes in 23 days.