9.9 is larger than 9.11.

Here's why: 

When comparing decimal numbers, start from the left and compare each digit in the same place value.
- Both have 9 in the units place.
- The first decimal place: 9.11 has 1, and 9.9 has 9.

So 9.9 (which is 9.90) is **larger** than 9.11.
