Page 27 - Start Up Mathematics_6

Example 28: Find the estimated quotient for (a) 477 ÷ 19 (b) 862 ÷ 29
Solution: (a) Rounding off each number to the greatest place:

477 rounded off to the nearest hundreds is 500.
19 rounded off to the nearest tens is 20.
Therefore, estimated quotient = 500 ÷ 20 = 25
(b) Rounding off each number to the greatest place:
862 rounded off to the nearest hundreds is 900.
29 rounded off to the nearest tens is 30.
Therefore, estimated quotient = 900 ÷ 30 = 30

EXERCISE 1.3

1. Estimate each of the following sum to its nearest tens:
(a) 67 + 40 (b) 78 + 43 (c) 881 + 728 (d) 567 + 432
2. Estimate each of the following sum to its nearest hundreds:
(a) 367 + 564 (b) 872 + 569 (c) 852 + 769 (d) 5,139 + 7,653
3. Estimate each of the following sum to its 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 its nearest tens:
(a) 67 – 43 (b) 689 – 432 (c) 564 – 321 (d) 856 – 672
5. Estimate each of the following difference to its nearest hundreds:
(a) 674 – 432 (b) 689 – 532 (c) 764 – 321 (d) 956 – 572
6. Estimate each of the following difference to its 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 its 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 its nearest hundreds:
(a) 581 × 456 (b) 167 × 233 (c) 478 × 132 (d) 223 × 198
9. Estimate the following products using 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

Brackets
Vani bought 5 sketch pens from a stationery shop for ` 3 each. Vani’s brother Nikhil bought
7 sketch pens for ` 3 each. Vani calculated that the total money spent by them is 5 × 3 + 7 × 3 =
15 + 21 = 36, i.e., ` 36. Nikhil calculated it by a different method but got the same amount, i.e.,
(5 + 7) × 3 = 12 × 3 = 36, i.e., ` 36. Nikhil combined the total number of pens, i.e., 5 + 7 and
treated it as a single number by putting brackets and then multiplied it by the cost of 1 pen, i.e.,
` 3. The rule is to first simplify everything in the bracket to a single number and then perform
the other operations outside.

19