Problem Breakdown and Solution
The task involves two main parts:
1.
Rounding numbers to the nearest ten.
2.
Estimating sums and differences by rounding to the nearest ten.
Let's solve each part step by step.
---
####
Part 1: Rounding to the Nearest Ten
To round a number to the nearest ten:
- Look at the digit in the ones place.
- If it is 5 or greater, round up.
- If it is less than 5, round down.
##### Numbers to Round:
1.
21: The ones digit is 1 (less than 5), so round down to
20.
2.
85: The ones digit is 5, so round up to
90.
3.
72: The ones digit is 2 (less than 5), so round down to
70.
4.
451: The ones digit is 1 (less than 5), so round down to
450.
5.
409: The ones digit is 9 (5 or greater), so round up to
410.
6.
434: The ones digit is 4 (less than 5), so round down to
430.
7.
173: The ones digit is 3 (less than 5), so round down to
170.
8.
585: The ones digit is 5, so round up to
590.
9.
328: The ones digit is 8 (5 or greater), so round up to
330.
10.
1,214: The ones digit is 4 (less than 5), so round down to
1,210.
11.
2,357: The ones digit is 7 (5 or greater), so round up to
2,360.
12.
3,286: The ones digit is 6 (5 or greater), so round up to
3,290.
##### Final Rounded Values:
```
21 → 20
85 → 90
72 → 70
451 → 450
409 → 410
434 → 430
173 → 170
585 → 590
328 → 330
1,214 → 1,210
2,357 → 2,360
3,286 → 3,290
```
---
####
Part 2: Estimating Sums and Differences
For each sum or difference, round the numbers to the nearest ten first, then perform the operation.
##### Sum/Difference 1:
184 + 152
- Round 184 to the nearest ten:
180
- Round 152 to the nearest ten:
150
- Estimate: \( 180 + 150 = 330 \)
##### Sum/Difference 2:
276 - 173
- Round 276 to the nearest ten:
280
- Round 173 to the nearest ten:
170
- Estimate: \( 280 - 170 = 110 \)
##### Sum/Difference 3:
350 + 116
- Round 350 to the nearest ten:
350 (already a multiple of 10)
- Round 116 to the nearest ten:
120
- Estimate: \( 350 + 120 = 470 \)
##### Sum/Difference 4:
548 + 224
- Round 548 to the nearest ten:
550
- Round 224 to the nearest ten:
220
- Estimate: \( 550 + 220 = 770 \)
##### Sum/Difference 5:
673 - 148
- Round 673 to the nearest ten:
670
- Round 148 to the nearest ten:
150
- Estimate: \( 670 - 150 = 520 \)
##### Sum/Difference 6:
436 - 132
- Round 436 to the nearest ten:
440
- Round 132 to the nearest ten:
130
- Estimate: \( 440 - 130 = 310 \)
---
####
Final Answers for Part 2:
```
184 + 152 ≈ 330
276 - 173 ≈ 110
350 + 116 ≈ 470
548 + 224 ≈ 770
673 - 148 ≈ 520
436 - 132 ≈ 310
```
---
Boxed Final Answer:
#### Part 1:
```
21 → 20, 85 → 90, 72 → 70, 451 → 450, 409 → 410, 434 → 430, 173 → 170, 585 → 590, 328 → 330, 1,214 → 1,210, 2,357 → 2,360, 3,286 → 3,290
```
#### Part 2:
```
184 + 152 ≈ 330
276 - 173 ≈ 110
350 + 116 ≈ 470
548 + 224 ≈ 770
673 - 148 ≈ 520
436 - 132 ≈ 310
```
Final Boxed Answer:
\[
\boxed{
\begin{array}{l}
\text{Part 1: } 20, 90, 70, 450, 410, 430, 170, 590, 330, 1,210, 2,360, 3,290 \\
\text{Part 2: } 330, 110, 470, 770, 520, 310
\end{array}
}
\]
Parent Tip: Review the logic above to help your child master the concept of estimation maths worksheet.
