To determine how many cartons of milk you need to make 50 hot lattes, follow these steps:

1. Amount of milk per latte: 200 ml.
2. Total number of lattes: 50.

The total amount of milk required for 50 lattes is: $\text{Total milk} = 200 \, \text{ml/latte} \times 50 \, \text{lattes} = 10,000 \, \text{ml}$

Since 1 liter (L) is equivalent to 1,000 ml, the total milk needed in liters is: $\frac{10,000 \, \text{ml}}{1,000} = 10 \, \text{liters}$

Each carton contains 1 liter, so you'll need: $\frac{10 \, \text{liters}}{1 \, \text{liter/carton}} = 10 \, \text{cartons}$

Answer: You need 10 cartons of milk to make 50 hot lattes.

Would you like a breakdown of any steps or more details?

---

Here are 5 related questions:

1. What if you want to make 100 hot lattes?
2. How many lattes can you make with 5 cartons of milk?
3. How would the number of cartons change if each latte used 250 ml of milk?
4. How much milk is left over if you only use 9 cartons?
5. What is the cost per latte if each milk carton costs $3?

Tip: Keep in mind that 1 liter equals 1,000 milliliters to easily convert between these units.