1 cut into little pieces
One head of lettuce should feed 8-10 people, so for 50 people factor 5-6 heads of lettuce.
13 pounds
You don't mention whether this is for salad or for sandwiches. For side salads, you would need 12 to 14 medium size heads of lettuce for 100 people.
8 for tomatoes and 4 lettuce heads
a billion
8-10 heads of lettuce depending on how much lettuce you use
For a gathering of 22 people, you would typically need about 2 to 3 heads of romaine lettuce, depending on the size of the heads and how the lettuce will be served (as a salad or as part of a larger dish). If each person is expected to have a generous serving, aim for 3 heads. If it’s a side salad or part of a mixed dish, 2 heads should suffice. Always consider the appetite of your guests and any other dishes being served.
if it's only lettuce, then 35 heads ish. could be less. depends on the lettuce, what you're making and how hungery the people are.
28 = (70 / 5) * 2
100... rabbits? kids? zombies?
This depends upon portion size, the type of lettuce you and how many other ingredients are in the salad. Generally you decide on a recipe and, according to how many portions it will serve, multiply the amount of lettuce per portion by 70.
The number of lettuce heads needed for 40 burgers depends on how much lettuce you plan to use per burger. Typically, one head of lettuce can yield about 10 to 12 burger-sized leaves. Therefore, for 40 burgers, you would need around 4 to 5 heads of lettuce to ensure you have enough for each burger.