To calculate the number of laps per day, divide the total number of laps (100) by the number of days (4):

$\frac{100 \text{ laps}}{4 \text{ days}} = 25 \text{ laps per day}$

So, you need to do 25 laps per day.

Would you like more details or have any questions? Here are five related questions:

1. How many laps would you do in 6 days if you kept the same daily rate?
2. If you did 30 laps per day, how many total laps would you complete in 4 days?
3. How many days would it take to complete 200 laps at 25 laps per day?
4. What is the average speed per lap if you finish 25 laps in 2 hours?
5. How many laps can you complete in 2 days if you increase by 5 laps each day?

Tip: To quickly calculate average rates, divide the total quantity by the number of units (time, distance, etc.).