Hints:

1. When building the largest or smallest number, remember: the digits at the beginning (highest place value) have the biggest impact on the final result.

2. To make the number as large as possible, aim to start with 55 in the highest-order digits.

3. To make the number as small as possible, try beginning with 111 in the first three positions.

Solution:

To make the number as large as possible, we need to prioritize placing 5’s in the highest-order digits.

• Start by removing digits 1 through 4 from the first two sets.

• This leaves: 55123451234512345

• The next best digits to remove are 1 and 2, giving the final result:
  553451234512345

To make the number as small as possible, we want the number to begin with 1’s.

• Remove the first two groups of 2 through 5, resulting in: 11123451234512345

• Then remove 4 and 5 to lower the value further, producing the smallest number:
  111231234512345