Page 40 - Start Up Mathematics_3
P. 40
Estimating the Sum (by rounding off)
Estimation gives a rough or approximate value of the sum. To estimate the given sum,
round off the numbers and add. Th H T O
Example 4: Twinkle has 4536 stamps of India, 2102 stamps 1 4 5 4 0
of USA and 1938 stamps of UK. Estimate the 2 1 0 0
number of stamps she has if she rounds off all
the numbers to the nearest 10. + 1 9 4 0
Solution: Twinkle has approximately 8 5 8 0
Stamps of India = 4540 (4536 gets rounded off to 4540)
Stamps of USA = 2100 (2102 gets rounded off to 2100)
Stamps of UK = 1940 (1938 gets rounded off to 1940)
So, total stamps with Twinkle = 4540 + 2100 + 1940
= 8580 (estimated value)
EXERCISE 3.3
1. Add using the expanded form.
Expanded form
(a) Th H T O Th H T O
4 8 2 6 + + +
+ 2 7 9 5 + + +
+ + +
+
Expanded form
(b) Th H T O Th H T O
3 7 9 4 + + +
+ 5 8 6 3 + + +
+ + +
+
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