Estimating sums and differences
✩
Round the numbers to the leading digit. Estimate the sum or difference.
3,576 → 4,000
+ 1,307 → +1,000
5,000
is about
198,248 → 200,000
– 116,431 → –1,00,000
100,000
is about
Round the numbers to the leading digit. Estimate the sum or difference.
685 →
+ 489 →
is about
21,481 →
– 12,500 →
is about
7,834 →
+ 3,106 →
is about
682,778 →
+ 130,001 →
is about
58,499 →
– 22,135 →
is about
902,276 →
– 615,999 →
is about
46,801 →
+ 34,700 →
is about
9,734 →
– 8,306 →
is about
65,606 →
+ 85,943 →
is about
5,218 →
– 3,673 →
is about
745 →
+ 451 →
is about
337,297 →
– 168,931 →
is about
Write < or > for each problem.
329 + 495
800
11,569 – 6,146
6,000
563 – 317
300
8,193 – 6,668
1,000
41,924 – 12,445
50,000
634,577 + 192,556
800,000
18,885 + 12,691
30,000
713,096 – 321,667
400,000
© Dorling Kindersley Limited [2010]
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✩
Estimating sums and differences
1
2
Round the numbers to the leading digit. Estimate the sum or difference.
0
198,248 → 200,000
– 116,431 → – 100,000
100,000
is about
7
6
Round the numbers to the leading digit. Estimate the sum or difference.
21,481 →
– 12,500 →
is about
700
+ 500
1,200
682,778 → 700,000
+ 130,001 → + 100,000
800,000
is about
50,000
46,801 →
+ 34,700 → + 30,000
80,000
is about
5,218 →
– 3,673 →
is about
5,000
– 4,000
1,000
7,834 →
+ 3,106 →
is about
20,000
– 10,000
10,000
8,000
+ 3,000
11,000
60,000
58,499 →
– 22,135 → – 20,000
40,000
is about
902,276 → 900,000
– 615,999 → – 600,000
300,000
is about
9,734 →
– 8,306 →
is about
10,000
– 8,000
2,000
70,000
65,606 →
+ 85,943 → + 90,000
160,000
is about
745 →
+ 451 →
is about
700
+ 500
1,200
337,297 → 300,000
– 168,931 → – 200,000
100,000
is about
8
1
3
685 →
+ 489 →
is about
9
5
3,576 → 4,000
+ 1,307 → + 1,000
5,000
is about
4
9
2
Write < or > for each problem.
800
11,569 – 6,146
<
6,000
563 – 317
<
300
8,193 – 6,668
>
1,000
41,924 – 12,445
<
50,000
634,577 + 192,556
>
800,000
18,885 + 12,691
>
30,000
713,096 – 321,667
<
400,000
8
7
3
115
3
>
2
329 + 495
2
7
5
6
9
0
3
4
1
9
2
6 carefully if the
In section 2, children need to think about their estimates more
estimate is very close to the number on the right side of the equation. Have
them look at the numbers in the next place to the right to adjust their estimates
up or down.
© Dorling Kindersley Limited [2010]
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