To solve this problem, we need to transfer all the water from the large container (12 liters) into the smaller one (which holds 750 milliliters at a time). First, let's break the quantities into compatible units and use fraction operations.

Step 1: Convert 12 liters to milliliters

Since 1 liter = 1000 milliliters, we convert 12 liters to milliliters: $12 \text{ liters} = 12 \times 1000 = 12000 \text{ milliliters}$

Step 2: Set up the division as a fraction

To find out how many times the smaller container needs to be filled, we divide the total water in milliliters by the capacity of the smaller container: $\frac{12000 \text{ milliliters}}{750 \text{ milliliters}} = \frac{12000}{750}$

Step 3: Simplify the fraction

We simplify the fraction: $\frac{12000}{750} = \frac{12000 \div 250}{750 \div 250} = \frac{48}{3} = 16$

Conclusion:

John will need to fill the smaller container 16 times to completely transfer all the water.

Would you like more details or have any questions?

Here are 5 related questions for practice:

1. How many times would John need to fill a 500 milliliter container instead of 750 milliliters?
2. If John had a 10-liter container, how many times would he need to transfer with the 750 milliliter container?
3. How much water remains in the large container if John fills the small container only 10 times?
4. Convert 5 liters to milliliters and calculate how many times a 250 milliliter container would need to be filled to transfer that amount of water.
5. If John can fill the smaller container 5 times per minute, how long will it take him to transfer all the water?

Tip: Always convert units to be compatible (e.g., liters to milliliters) before solving word problems.