Here are the solutions for the estimation problems. To solve these, we round each number to the nearest hundred and then add or subtract.
Rounding Rule:
* Look at the tens digit (the second number from the right).
* If it is
5 or more, round up.
* If it is
4 or less, round down (keep the hundreds digit the same).
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2) 4757 + 1818
* Round 4757: The tens digit is 5, so round up to
4800.
* Round 1818: The tens digit is 1, so round down to
1800.
* Estimate: $4800 + 1800 =$
6600
3) 1586 + 8284
* Round 1586: The tens digit is 8, so round up to
1600.
* Round 8284: The tens digit is 8, so round up to
8300.
* Estimate: $1600 + 8300 =$
9900
4) 9581 - 3664
* Round 9581: The tens digit is 8, so round up to
9600.
* Round 3664: The tens digit is 6, so round up to
3700.
* Estimate: $9600 - 3700 =$
5900
5) 5473 - 2351
* Round 5473: The tens digit is 7, so round up to
5500.
* Round 2351: The tens digit is 5, so round up to
2400.
* Estimate: $5500 - 2400 =$
3100
6) 5243 + 8775
* Round 5243: The tens digit is 4, so round down to
5200.
* Round 8775: The tens digit is 7, so round up to
8800.
* Estimate: $5200 + 8800 =$
14000
7) 7467 + 9269
* Round 7467: The tens digit is 6, so round up to
7500.
* Round 9269: The tens digit is 6, so round up to
9300.
* Estimate: $7500 + 9300 =$
16800
8) 6834 - 1457
* Round 6834: The tens digit is 3, so round down to
6800.
* Round 1457: The tens digit is 5, so round up to
1500.
* Estimate: $6800 - 1500 =$
5300
9) 7845 - 2669
* Round 7845: The tens digit is 4, so round down to
7800.
* Round 2669: The tens digit is 6, so round up to
2700.
* Estimate: $7800 - 2700 =$
5100
10) 6494 + 6556
* Round 6494: The tens digit is 9, so round up to
6500.
* Round 6556: The tens digit is 5, so round up to
6600.
* Estimate: $6500 + 6600 =$
13100
11) 4234 - 3468
* Round 4234: The tens digit is 3, so round down to
4200.
* Round 3468: The tens digit is 6, so round up to
3500.
* Estimate: $4200 - 3500 =$
700
12) 7117 + 5394
* Round 7117: The tens digit is 1, so round down to
7100.
* Round 5394: The tens digit is 9, so round up to
5400.
* Estimate: $7100 + 5400 =$
12500
13) 4824 - 3873
* Round 4824: The tens digit is 2, so round down to
4800.
* Round 3873: The tens digit is 7, so round up to
3900.
* Estimate: $4800 - 3900 =$
900
14) 2328 + 9627
* Round 2328: The tens digit is 2, so round down to
2300.
* Round 9627: The tens digit is 2, so round down to
9600.
* Estimate: $2300 + 9600 =$
11900
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Final Answer:
2) 6600
3) 9900
4) 5900
5) 3100
6) 14000
7) 16800
8) 5300
9) 5100
10) 13100
11) 700
12) 12500
13) 900
14) 11900
Parent Tip: Review the logic above to help your child master the concept of estimating sums worksheet 3rd grade.
