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example: Rounding off 568 to the nearest hundred 600

Rounding off 8177 to the nearest thousand 8000
Rounding off 28139 to the nearest ten thousand 30000

Rounding off 150000 to the nearest lakh 200000

Sometimes in real life situations, we need a quick answer. In such situations estimation helps.
Sometimes, the actual addition, subtraction, multiplication or division of the numbers takes
more time to calculate. In these cases, we find the estimated sum, difference, product, or
quotient by rounding off the numbers to the nearest tens, hundreds, thousands and so on.

example 1: Estimate the answer of each of the following.

(a) 2,960 + 1,730 (b) 9,300 – 6,420 (c) 4,465 × 8 (d) 24,581 ÷ 47

Solution:

(a) rounded to estimated sum Actual sum
2960 nearest 1000 3000 3 0 0 0 2 9 6 0

rounded to + 2 0 0 0 + 1 7 3 0
1730 nearest 1000 2000 5 0 0 0 4 6 9 0

The estimated sum is close to the actual sum.

(b) rounded to estimated difference Actual difference
9300 nearest 1000 9000 9 0 0 0 8 12 10

rounded to – 6 0 0 0 9 3 0 0
6420 nearest 1000 6000 3 0 0 0 – 6 4 2 0
2 8 8 0

The estimated difference is close to the actual difference.

(c) rounded to
4465 nearest 1000 4000 estimated product Actual product

rounded to × 4 0 0 0 × 4 4 6 5
1 0
8
8 nearest 10 10 4 0 0 0 0 3 5 7 2 0

The estimated product is close to the actual product.

(d) estimated quotient Actual quotient

24581 25000 (Rounding off to the nearest thousand) 5 2 3
2 4 5 8 1
47 50 (Rounding off to the nearest ten) 47 2 3 5
25,000 ÷ 50 = 500 1 0 8
9 4
1 4 1

The estimated quotient is close to the actual quotient. 1 4 1
0

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