# Estimate Sums and Differences

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In this pdf, you will learn to estimate sums and differences using the method of rounding the number to the leading digit.
1. Estimating sums and differences ✩
Round the numbers to the leading digit. Estimate the sum or difference.
3,576 → 4,000 198,248 → 200,000
+ 1,307 → +1,000 – 116,431 → –1,00,000
is about 5,000 is about 100,000
Round the numbers to the leading digit. Estimate the sum or difference.
685 → 21,481 → 7,834 →
+ 489 → – 12,500 → + 3,106 →
is about is about is about
682,778 → 58,499 → 902,276 →
+ 130,001 → – 22,135 → – 615,999 →
is about is about is about
46,801 → 9,734 → 65,606 →
+ 34,700 → – 8,306 → + 85,943 →
is about is about is about
5,218 → 745 → 337,297 →
– 3,673 → + 451 → – 168,931 →
is about is about 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
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Round the numbers to the leading digit. Estimate the sum or difference. 2 4
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3,576 → 4,000 198,248 → 200,000
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+ 1,307 → + 1,000 – 116,431 → – 100,000 8
is about 5,000 is about 100,000 9
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Round the numbers to the leading digit. Estimate the sum or difference. 6 12
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685 → 700 21,481 → 20,000 7,834 → 8,000 15
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+ 489 → + 500 – 12,500 → – 10,000 + 3,106 → + 3,000 16
is about 1,200 is about 10,000 is about 11,000 17
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682,778 → 700,000
+ 130,001 → + 100,000
58,499 → 60,000
– 22,135 → – 20,000
902,276 → 900,000
– 615,999 → – 600,000
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is about 800,000 is about 40,000 is about 300,000 22
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46,801 → 50,000 9,734 → 10,000 65,606 → 70,000
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+ 34,700 → + 30,000 – 8,306 → – 8,000 + 85,943 → + 90,000
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is about 80,000 is about 2,000 is about 160,000
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5,218 →
– 3,673 →
5,000
– 4,000
745 →
+ 451 →
700
+ 500
337,297 → 300,000
– 168,931 → – 200,000
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is about 1,000 is about 1,200 is about 100,000
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Write < or > for each problem. 36
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329 + 495 > 800 11,569 – 6,146 < 6,000 3 38
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563 – 317 < 300 8,193 – 6,668 > 1,000
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41,924 – 12,445 < 50,000 634,577 + 192,556 > 800,000
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18,885 + 12,691 > 30,000 713,096 – 321,667 < 400,000
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In section 2, children need to think about their estimates more
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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]