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KENDRIYA VIDYALAYA, NTPC RIHAND NAGAR
MOHAMMAD RIZWAN (H.M.)
Class – IV
Subject – Mathematics
Unit – 6 Addition Subtraction
Topic – Estimating Sums and Difference
ESTIMATING SUMS
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Round The Number To The Nearest 10 And Add
1. 70 ------- 73 ----- 75 ------------- 80
2. 40 ----------------- 45 ------- 49 - 50
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73 70
+ 49 +50
122 120
Answer : Actual - 122 Estimate - 120
Round The Number To The Nearest 100 And Add
1. 100 -------------- 150 ----154 ------- 200
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154 200
+ 129 + 100
283 300
Answer : Actual – 283 Estimate - 300
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Round The Number To The Nearest 1000 And Add
1. 1000 ------------ 1500 ----1705 ------ 2000
1 1 1 1 1
31703 32000
+ 47807 + 48000
+ 11397 + 11000
90907 91000
Answer : Actual – 90907 Estimate - 91000
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Exercise
69 42 57
+ 78 + 37 + 74
. . .
(b) Nearest 100
4160 7358
+ 2397 + 5763
. .
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Exercise
(c) Nearest 1000
26379 6942 1
+ 76689 + 43587
. .
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ESTIMATING DIFFERENCES
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Estimate the difference to the nearest 10 And Subtract
Solution-
E.g. 8 12
1 9 2 1 9 0
- 1 6 8 - 1 7 0
0 2 4 0 2 0
Ans: Actual-24 Estimate-20
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Example 2
8 12
9 2 9 0
- 3 5 - 4 0
5 7 5 0
Ans: Actual-57 Estimate-50
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Estimate the difference to the nearest 100 And Subtract
Solution-
E.g. 6 12 6 13
7 2 9 8 7 3 0 0
- 2 5 6 1 - 2 6 0 0
4 7 3 7 4 7 0 0
Ans: Actual-4737 Estimate-4700
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Estimate the difference to the nearest 1000 And Subtract
Solution-
E.g. 4 10
5 7 5 0 9 5 8 0 0 0
- 4 1 3 9 9 - 4 1 0 0 0
1 6 1 1 0 1 7 0 0 0
Ans:Actual-1610 Estimate-1700
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Exercise
9 1 8 5 6
- 6 8 - 1 3 9
___ ____
(b) Nearest hundred
6 1 5 8 4 6 7 2
- 4 4 2 9 - 1 0 8 5
_____ _____
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(c) Nearest thousands�� 4 5 6 5 0� - 2 4 7 5 6� _______�
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