How many bottles of wine to serve 100?

For 100 guests, you will need approximately 100 bottles of wine. Here's a more detailed calculation:

1 bottle of wine (750 ml) has 5 glasses.

100 guests / 5 glasses per bottle = 20 bottles per 5 guests.

Since there are likely to be more than 5 guests drinking wine, rounding up to 25 bottles per 5 guests is more appropriate.

25 bottles X 4 groups = 100 bottles.

Of course, the number of bottles needed can vary depending on factors like the type of wine (red or white), the preferences of your guests, and whether or not you're serving other alcoholic beverages. It's always better to have a few extra bottles on hand than run out.