This worksheet provides structured practice for estimating addition sums by rounding numbers to specific place values.

Problem Overview:

The task involves estimating the sums of given numbers by rounding them off to the nearest hundred or thousand, as specified. Let's break it down step by step.

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Part 1: Estimating Addition by Rounding Off to the Nearest Hundred

#### Step 1: Understand Rounding to the Nearest Hundred
- If the tens digit is 5 or greater, round up.
- If the tens digit is less than 5, round down.

#### Step 2: Solve Each Problem

##### Problem 1:
$$
324 + 454
$$
- Round 324 to the nearest hundred: \(324 \rightarrow 300\)
- Round 454 to the nearest hundred: \(454 \rightarrow 500\)
- Estimated sum: \(300 + 500 = 800\)

##### Problem 2:
$$
965 + 457
$$
- Round 965 to the nearest hundred: \(965 \rightarrow 1000\)
- Round 457 to the nearest hundred: \(457 \rightarrow 500\)
- Estimated sum: \(1000 + 500 = 1500\)

##### Problem 3:
$$
325 + 247
$$
- Round 325 to the nearest hundred: \(325 \rightarrow 300\)
- Round 247 to the nearest hundred: \(247 \rightarrow 200\)
- Estimated sum: \(300 + 200 = 500\)

##### Problem 4:
$$
365 + 124
$$
- Round 365 to the nearest hundred: \(365 \rightarrow 400\)
- Round 124 to the nearest hundred: \(124 \rightarrow 100\)
- Estimated sum: \(400 + 100 = 500\)

##### Problem 5:
$$
365 + 247
$$
- Round 365 to the nearest hundred: \(365 \rightarrow 400\)
- Round 247 to the nearest hundred: \(247 \rightarrow 200\)
- Estimated sum: \(400 + 200 = 600\)

##### Problem 6:
$$
987 + 214
$$
- Round 987 to the nearest hundred: \(987 \rightarrow 1000\)
- Round 214 to the nearest hundred: \(214 \rightarrow 200\)
- Estimated sum: \(1000 + 200 = 1200\)

##### Problem 7:
$$
632 + 247
$$
- Round 632 to the nearest hundred: \(632 \rightarrow 600\)
- Round 247 to the nearest hundred: \(247 \rightarrow 200\)
- Estimated sum: \(600 + 200 = 800\)

##### Problem 8:
$$
987 + 247
$$
- Round 987 to the nearest hundred: \(987 \rightarrow 1000\)
- Round 247 to the nearest hundred: \(247 \rightarrow 200\)
- Estimated sum: \(1000 + 200 = 1200\)

##### Problem 9:
$$
365 + 247
$$
- Round 365 to the nearest hundred: \(365 \rightarrow 400\)
- Round 247 to the nearest hundred: \(247 \rightarrow 200\)
- Estimated sum: \(400 + 200 = 600\)

---

Part 2: Estimating Addition by Rounding Off to the Nearest Thousand

#### Step 1: Understand Rounding to the Nearest Thousand
- If the hundreds digit is 5 or greater, round up.
- If the hundreds digit is less than 5, round down.

#### Step 2: Solve Each Problem

##### Problem 1:
$$
2547 + 3214
$$
- Round 2547 to the nearest thousand: \(2547 \rightarrow 3000\)
- Round 3214 to the nearest thousand: \(3214 \rightarrow 3000\)
- Estimated sum: \(3000 + 3000 = 6000\)

##### Problem 2:
$$
3214 + 1247
$$
- Round 3214 to the nearest thousand: \(3214 \rightarrow 3000\)
- Round 1247 to the nearest thousand: \(1247 \rightarrow 1000\)
- Estimated sum: \(3000 + 1000 = 4000\)

##### Problem 3:
$$
3698 + 2471
$$
- Round 3698 to the nearest thousand: \(3698 \rightarrow 4000\)
- Round 2471 to the nearest thousand: \(2471 \rightarrow 2000\)
- Estimated sum: \(4000 + 2000 = 6000\)

##### Problem 4:
$$
3254 + 2478
$$
- Round 3254 to the nearest thousand: \(3254 \rightarrow 3000\)
- Round 2478 to the nearest thousand: \(2478 \rightarrow 2000\)
- Estimated sum: \(3000 + 2000 = 5000\)

##### Problem 5:
$$
9874 + 3254
$$
- Round 9874 to the nearest thousand: \(9874 \rightarrow 10000\)
- Round 3254 to the nearest thousand: \(3254 \rightarrow 3000\)
- Estimated sum: \(10000 + 3000 = 13000\)

##### Problem 6:
$$
3247 + 7841
$$
- Round 3247 to the nearest thousand: \(3247 \rightarrow 3000\)
- Round 7841 to the nearest thousand: \(7841 \rightarrow 8000\)
- Estimated sum: \(3000 + 8000 = 11000\)

##### Problem 7:
$$
9654 + 3254
$$
- Round 9654 to the nearest thousand: \(9654 \rightarrow 10000\)
- Round 3254 to the nearest thousand: \(3254 \rightarrow 3000\)
- Estimated sum: \(10000 + 3000 = 13000\)

##### Problem 8:
$$
4875 + 4214
$$
- Round 4875 to the nearest thousand: \(4875 \rightarrow 5000\)
- Round 4214 to the nearest thousand: \(4214 \rightarrow 4000\)
- Estimated sum: \(5000 + 4000 = 9000\)

##### Problem 9:
$$
2321 + 1245
$$
- Round 2321 to the nearest thousand: \(2321 \rightarrow 2000\)
- Round 1245 to the nearest thousand: \(1245 \rightarrow 1000\)
- Estimated sum: \(2000 + 1000 = 3000\)

---

Final Answer:

$$
\boxed{
\begin{array}{l}
\text{Nearest Hundred:} \\
800, 1500, 500, 500, 600, 1200, 800, 1200, 600 \\
\text{Nearest Thousand:} \\
6000, 4000, 6000, 5000, 13000, 11000, 13000, 9000, 3000
\end{array}
}
$$