Decimal Range
1. **State the problem:** We need to use three digits from the cards {6, 0, 5, 9, 8} to create a decimal number $0.\text{abc}$ such that it satisfies
$$\frac{57}{100} < 0.\text{abc} < \frac{64}{100}$$
which means
$$0.57 < 0.\text{abc} < 0.64$$
2. **Analyze constraints:** The decimal must be greater than 0.57 and less than 0.64.
3. **Step-by-step search:**
- The first digit after decimal (a) must be 5 or 6 because digits 0-9 are available.
- If we pick $a=5$, then the decimal looks like 0.5bc and must be greater than 0.57, so digits b and c combined must make it > 0.57.
- Using available digits: 6,0,5,9,8
Try 0.58x: 0.58 is 0.58>0.57 and less than 0.64, so that's good. Use 8 from the digits, and then for c, pick any remaining digit (e.g., 0 or 5).
Trying 0.589 (digits 5,8,9): 0.589 is greater than 0.57 and less than 0.64.
4. **Answer:** A valid decimal is 0.589 using digits 5, 8, and 9 from the cards.
5. **Summary:**
- Three digits chosen: 5, 8, 9
- Decimal formed: $0.589$
- Inequality check: $0.57 < 0.589 < 0.64$ (True)
Hence, $\boxed{0.589}$ is a valid decimal number meeting the criteria.