Clear guide to understanding place value, featuring a chart for the number 2,146,807 and practice questions for students.

Problem Analysis:

The task involves understanding place value in numbers. The worksheet provides a chart that explains the place values of digits in a number, ranging from "Ones" to "Ten Millions." The goal is to identify and calculate the value of specific digits based on their positions in the given numbers.

Key Concepts:

1. Place Value: Each digit in a number has a value based on its position.
- For example, in the number 2,345:
- The digit "2" is in the Thousands place, so its value is \(2 \times 1,000 = 2,000\).
- The digit "3" is in the Hundreds place, so its value is \(3 \times 100 = 300\).
- The digit "4" is in the Tens place, so its value is \(4 \times 10 = 40\).
- The digit "5" is in the Ones place, so its value is \(5 \times 1 = 5\).

2. Identifying Digits: We need to locate specific digits in the given numbers and determine their values based on their positions.

---

Solution to Each Question:

#### Question 1: Which digit in this number has the least value?
- Number: 2,345
- Analysis:
- The digit "2" is in the Thousands place (\(2,000\)).
- The digit "3" is in the Hundreds place (\(300\)).
- The digit "4" is in the Tens place (\(40\)).
- The digit "5" is in the Ones place (\(5\)).
- Conclusion: The digit with the least value is "5" because it is in the Ones place.

#### Question 2: Which digit in this number has the greatest value?
- Number: 2,345
- Analysis:
- The digit "2" is in the Thousands place (\(2,000\)).
- The digit "3" is in the Hundreds place (\(300\)).
- The digit "4" is in the Tens place (\(40\)).
- The digit "5" is in the Ones place (\(5\)).
- Conclusion: The digit with the greatest value is "2" because it is in the Thousands place.

#### Question 3: What is the value of the digit in the thousands place?
- Number: 2,345
- Analysis:
- The digit in the Thousands place is "2".
- The value of this digit is \(2 \times 1,000 = 2,000\).
- Conclusion: The value of the digit in the Thousands place is 2,000.

#### Question 4: What is the value of the digit in the hundred-thousands place?
- Number: 2,345
- Analysis:
- The number 2,345 does not have a digit in the Hundred-Thousands place because it only has four digits.
- Therefore, the value of the digit in the Hundred-Thousands place is 0 (since there is no digit there).
- Conclusion: The value of the digit in the Hundred-Thousands place is 0.

---

Final Answers:

1. The digit with the least value is 5.
2. The digit with the greatest value is 2.
3. The value of the digit in the Thousands place is 2,000.
4. The value of the digit in the Hundred-Thousands place is 0.

Boxed Final Answer:

\[
\boxed{5, 2, 2000, 0}
\]