Page 28 - ICSE Math 6

(b) 5,281 × 3,849
Let’s round off each factor to its greatest place.

5,281 rounded off to the nearest thousands is 5,000.
5,000
3,849 rounded off to the nearest thousands is 4,000. × 4,000
Therefore, the estimated product of 5,281 and 3,849 2,00,00,000
= 5,000 × 4,000 = 2,00,00,000

Example 21: Find the estimated quotient for 477 ÷ 19.
Solution: Rounding off each number to its greatest place.
477 rounded off to the nearest hundreds is 500.
19 rounded off to the nearest tens is 20.
Therefore, the estimated quotient = 500 ÷ 20 = 25

EXERCISE 1.4

1. Estimate each of the following sum to the nearest tens.
(a) 67 + 40 (b) 78 + 43 (c) 881 + 728 (d) 567 + 432

2. Estimate each of the following sum to the nearest hundreds.
(a) 367 + 564 (b) 872 + 569 (c) 852 + 769 (d) 5,139 + 7,653
3. Estimate each of the following sum to the nearest thousands.
(a) 56,784 + 76,834 (b) 43,829 + 34,784 (c) 24,568 + 54,118 (d) 21,384 + 45,379
4. Estimate each of the following difference to the nearest tens.

(a) 67 – 43 (b) 689 – 432 (c) 564 – 321 (d) 856 – 672
5. Estimate each of the following difference to the nearest hundreds.
(a) 674 – 432 (b) 689 – 532 (c) 764 – 321 (d) 956 – 572

6. Estimate each of the following difference to the nearest thousands.
(a) 7,674 – 3,432 (b) 3,689 – 2,532 (c) 6,764 – 5,321 (d) 8,956 – 7,572
7. Estimate the following products by rounding off each number to the nearest tens.
(a) 58 × 45 (b) 67 × 33 (c) 78 × 32 (d) 23 × 98
8. Estimate the following products by rounding off each number to the nearest hundreds.

(a) 581 × 456 (b) 167 × 233 (c) 478 × 132 (d) 223 × 198
9. Estimate the following products using the general rule.
(a) 345 × 46 (b) 3,427 × 456 (c) 2,192 × 479 (d) 9,876 × 32

10. Find the estimated quotient for each of the following.
(a) 567 ÷ 24 (b) 861 ÷ 29 (c) 347 ÷ 13 (d) 691 ÷ 18

AT A GLANCE

¾ Numerals are symbols used to represent numbers.
¾ The process of reading writing or naming numbers in words is called numeration.
¾ Face value of a digit in a number is the value of the digit itself.
¾ Place value of a digit = Face value × Value of the place of the digit

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