To calculate the number of laps per day, divide the total number of laps by the number of days:

$\frac{51 \text{ laps}}{3 \text{ days}} = 17 \text{ laps/day}$

So, the average number of laps per day is 17.

Would you like more details or have any questions?

Here are 5 related questions you could explore:

1. How many laps would be completed in 7 days at the same rate?
2. If the number of laps increased by 10% each day, how many laps would be completed on day 4?
3. How many laps would need to be done per day to complete 100 laps in 3 days?
4. How would the daily average change if 60 laps were completed in 3 days instead of 51?
5. What if the laps were spread unevenly across the 3 days?

Tip: When solving similar problems, ensure to divide the total by the exact number of periods to find the correct average per unit!