Final answer:
The number is a multiple of 5 but not 10, with the units and hundreds digits being the same and their sum being 11. Therefore, the number is 505.
Step-by-step explanation:
This question can be solved by analyzing the given clues. The number is a multiple of 5 but not 10, so it cannot end in 0. The units and hundreds digits are the same, meaning they both have to be a single digit number. Additionally, the sum of the three digits is 11.
Since the units and hundreds digits are the same, and their sum is 11, they both must be equal to 5. Thus, the number is 505.