1. **Problem Statement:** We need to find how many unique license plates can be formed with the format of three numbers followed by three letters, where both numbers and letters can repeat. 2. **Understanding the format:** The license plate format is: N N N L L L, where N represents a number and L represents a letter. 3. **Possible values:** - Numbers: Each number can be from 0 to 9, so there are 10 possible digits. - Letters: Each letter can be from A to Z, so there are 26 possible letters. 4. **Repetition allowed:** Since repetition is allowed, each position can be any of the possible values independently. 5. **Calculating total combinations:** - For the three numbers: $10 \times 10 \times 10 = 10^3 = 1000$ - For the three letters: $26 \times 26 \times 26 = 26^3 = 17576$ 6. **Total unique license plates:** Multiply the number combinations by the letter combinations: $$ 1000 \times 17576 = 17,576,000 $$ **Final answer:** There are 17,576,000 unique license plates possible when letters and numbers can repeat.