1. America: The ancient Roman numerals were very beautiful and symmetrical, such as Ⅳ for 4 and ⅶ for 8, which was very attractive visually.

2. convenient counting: ancient Roman numerals used a symbol to represent a number, which is convenient for counting. For example, I, II and III stand for 1, 2 and 3 respectively, thus avoiding the trouble of using multiple Arabic numerals.

However, ancient Roman numerals also had some shortcomings:

1. Non-decimal: Roman numerals are based on repeated combinations of seven symbols, not decimal. This makes it not intuitive and convenient to do some mathematical calculations.

2. There is no symbol indicating zero: there is no special symbol indicating zero in ancient Roman numerals, which brings some confusion and inconvenience to numerical operation.

3. Complex representation: Although ancient Roman numerals are convenient to use, the representation is more complicated. For example, you need to use different symbol combinations to represent numbers such as 6, 7, 8 and 9.

4. Can't be directly used in mathematical operations: ancient Roman numerals can't be directly used in mathematical operations and need to be converted. For example, addition and subtraction operations need to be converted into Arabic numerals for calculation, and then converted back to ancient Roman numerals.

Generally speaking, the advantages of ancient Roman numerals are beautiful and convenient to count, but there are also some disadvantages, such as non-decimal, no symbol indicating zero, complicated representation and not being directly used in mathematical operations.