Mental math practice sheet for adding and subtracting 10 and 100 from three-digit numbers.

Problem Explanation:

The task involves performing mental math operations on a set of numbers. Specifically, you need to:
1. Add 10 to each number.
2. Subtract 10 from each number.
3. Add 100 to each number.
4. Subtract 100 from each number.

The numbers provided are: 367, 785, 689, 890, 243, 338.

Solution Approach:

For each number, we will perform the four operations step by step:
- Add 10: Increase the number by 10.
- Subtract 10: Decrease the number by 10.
- Add 100: Increase the number by 100.
- Subtract 100: Decrease the number by 100.

Let's solve it for each number:

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#### Number: 367
1. Add 10: \( 367 + 10 = 377 \)
2. Subtract 10: \( 367 - 10 = 357 \)
3. Add 100: \( 367 + 100 = 467 \)
4. Subtract 100: \( 367 - 100 = 267 \)

#### Number: 785
1. Add 10: \( 785 + 10 = 795 \)
2. Subtract 10: \( 785 - 10 = 775 \)
3. Add 100: \( 785 + 100 = 885 \)
4. Subtract 100: \( 785 - 100 = 685 \)

#### Number: 689
1. Add 10: \( 689 + 10 = 699 \)
2. Subtract 10: \( 689 - 10 = 679 \)
3. Add 100: \( 689 + 100 = 789 \)
4. Subtract 100: \( 689 - 100 = 589 \)

#### Number: 890
1. Add 10: \( 890 + 10 = 900 \)
2. Subtract 10: \( 890 - 10 = 880 \)
3. Add 100: \( 890 + 100 = 990 \)
4. Subtract 100: \( 890 - 100 = 790 \)

#### Number: 243
1. Add 10: \( 243 + 10 = 253 \)
2. Subtract 10: \( 243 - 10 = 233 \)
3. Add 100: \( 243 + 100 = 343 \)
4. Subtract 100: \( 243 - 100 = 143 \)

#### Number: 338
1. Add 10: \( 338 + 10 = 348 \)
2. Subtract 10: \( 338 - 10 = 328 \)
3. Add 100: \( 338 + 100 = 438 \)
4. Subtract 100: \( 338 - 100 = 238 \)

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Final Answer:

Here is the completed table:

| Number | Add 10 | Subtract 10 | Add 100 | Subtract 100 |
|--------|--------|-------------|---------|---------------|
| 367 | 377 | 357 | 467 | 267 |
| 785 | 795 | 775 | 885 | 685 |
| 689 | 699 | 679 | 789 | 589 |
| 890 | 900 | 880 | 990 | 790 |
| 243 | 253 | 233 | 343 | 143 |
| 338 | 348 | 328 | 438 | 238 |

\boxed{
\begin{array}{|c|c|c|c|c|}
\hline
\text{Number} & \text{Add 10} & \text{Subtract 10} & \text{Add 100} & \text{Subtract 100} \\
\hline
367 & 377 & 357 & 467 & 267 \\
\hline
785 & 795 & 775 & 885 & 685 \\
\hline
689 & 699 & 679 & 789 & 589 \\
\hline
890 & 900 & 880 & 990 & 790 \\
\hline
243 & 253 & 233 & 343 & 143 \\
\hline
338 & 348 & 328 & 438 & 238 \\
\hline
\end{array}
}